Repository: projectdiscovery/nuclei

Issue:
Unnecessary template variable evaluation warnings during template discovery phase
### Description

When running Nuclei with template ID filters (e.g., `-id tech-detect`), warnings about failed variable expression evaluations appear for templates that are not being executed:

```bash
$ ./bin/nuclei -u https://scanme.sh -id tech-detect -vv -debug

[WRN] Failed to evaluate expression 'sha1(serial)': No parameter 'serial' found.
[WRN] Failed to evaluate expression 'replace(user, '.', '')': No parameter 'user' found.
[WRN] Failed to evaluate expression 'replace(user, '.', '')': No parameter 'user' found.
```

These warnings come from unrelated templates like:

- CVE-2023-6329.yaml
- tumblr.yaml
- smugmug.yaml

**Root Cause**:

The issue occurs during the `WorkflowLoader` initialization phase, where:

1. All templates are scanned during `WorkflowLoader` initialization to build an index for potential workflow references.
2. Variables are eagerly evaluated during YAML unmarshaling (`UnmarshalYAML`/`UnmarshalJSON`).
3. Evaluation happens with empty context (`map[string]interface{}{}`) at parse time.
4. Expressions fail when they reference runtime parameters that do NOT exist at parse time.

The current `checkForLazyEval()` only marks variables as lazy if they contain:

- Known runtime variables (`Host`, `BaseURL`, etc.).
- Special cases like `interactsh-url`.

It doesn't detect expressions that reference undefined parameters, causing eager eval to fail and produce warnings.



Discussion:

Solution patch:
diff --git a/.github/workflows/generate-pgo.yaml b/.github/workflows/generate-pgo.yaml
index b0c47d56..39fc7e6a 100644
--- a/.github/workflows/generate-pgo.yaml
+++ b/.github/workflows/generate-pgo.yaml
@@ -31,6 +31,7 @@ jobs:
       - uses: actions/checkout@v6
       - uses: projectdiscovery/actions/setup/git@v1
       - uses: projectdiscovery/actions/setup/go@v1
+      - uses: projectdiscovery/actions/cache/nuclei@v1
       - name: Generate list
         run: for i in {1..${{ matrix.targets }}}; do echo "https://honey.scanme.sh/?_=${i}" >> "${LIST_FILE}"; done
       # NOTE(dwisiswant0): use `-no-mhe` flag to get better samples.
diff --git a/.github/workflows/perf-regression.yaml b/.github/workflows/perf-regression.yaml
index 85650a09..78560672 100644
--- a/.github/workflows/perf-regression.yaml
+++ b/.github/workflows/perf-regression.yaml
@@ -14,6 +14,7 @@ jobs:
       - uses: actions/checkout@v6
       - uses: projectdiscovery/actions/setup/go@v1
       - uses: projectdiscovery/actions/cache/go-rod-browser@v1
+      - uses: projectdiscovery/actions/cache/nuclei@v1
       - run: make build-test
       - run: ./bin/nuclei.test -test.run - -test.bench=. -test.benchmem ./cmd/nuclei/ | tee $BENCH_OUT
         env:
diff --git a/.github/workflows/tests.yaml b/.github/workflows/tests.yaml
index e244b200..42a46a67 100644
--- a/.github/workflows/tests.yaml
+++ b/.github/workflows/tests.yaml
@@ -39,6 +39,7 @@ jobs:
       - uses: actions/checkout@v6
       - uses: projectdiscovery/actions/setup/go@v1
       - uses: projectdiscovery/actions/cache/go-rod-browser@v1
+      - uses: projectdiscovery/actions/cache/nuclei@v1
       - uses: projectdiscovery/actions/free-disk-space@v1
         with:
           llvm: 'false'
@@ -66,6 +67,7 @@ jobs:
       - uses: actions/checkout@v6
       - uses: projectdiscovery/actions/setup/go@v1
       - uses: projectdiscovery/actions/cache/go-rod-browser@v1
+      - uses: projectdiscovery/actions/cache/nuclei@v1
       - name: "Simple"
         run: go run .
         working-directory: examples/simple/
@@ -88,6 +90,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: projectdiscovery/actions/setup/go@v1
+      - uses: projectdiscovery/actions/cache/nuclei@v1
       - uses: projectdiscovery/actions/setup/python@v1
       - uses: projectdiscovery/actions/cache/go-rod-browser@v1
       - run: bash run.sh "${{ matrix.os }}"
@@ -108,6 +111,7 @@ jobs:
     steps:
       - uses: actions/checkout@v6
       - uses: projectdiscovery/actions/setup/go@v1
+      - uses: projectdiscovery/actions/cache/nuclei@v1
       - uses: projectdiscovery/actions/setup/python@v1
       - uses: projectdiscovery/actions/cache/go-rod-browser@v1
       - run: bash run.sh
diff --git a/go.mod b/go.mod
index 2317c601..8bd2a758 100644
--- a/go.mod
+++ b/go.mod
@@ -87,6 +87,7 @@ require (
 	github.com/leslie-qiwa/flat v0.0.0-20230424180412-f9d1cf014baa
 	github.com/lib/pq v1.10.9
 	github.com/mattn/go-sqlite3 v1.14.28
+	github.com/maypok86/otter/v2 v2.2.1
 	github.com/mholt/archives v0.1.5
 	github.com/microsoft/go-mssqldb v1.9.2
 	github.com/ory/dockertest/v3 v3.12.0
diff --git a/go.sum b/go.sum
index 3ad7a678..aa5d566c 100644
--- a/go.sum
+++ b/go.sum
@@ -707,6 +707,8 @@ github.com/mattn/go-sqlite3 v1.14.28 h1:ThEiQrnbtumT+QMknw63Befp/ce/nUPgBPMlRFEu
 github.com/mattn/go-sqlite3 v1.14.28/go.mod h1:Uh1q+B4BYcTPb+yiD3kU8Ct7aC0hY9fxUwlHK0RXw+Y=
 github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
 github.com/matttproud/golang_protobuf_extensions v1.0.4/go.mod h1:BSXmuO+STAnVfrANrmjBb36TMTDstsz7MSK+HVaYKv4=
+github.com/maypok86/otter/v2 v2.2.1 h1:hnGssisMFkdisYcvQ8L019zpYQcdtPse+g0ps2i7cfI=
+github.com/maypok86/otter/v2 v2.2.1/go.mod h1:1NKY9bY+kB5jwCXBJfE59u+zAwOt6C7ni1FTlFFMqVs=
 github.com/mholt/acmez v1.2.0 h1:1hhLxSgY5FvH5HCnGUuwbKY2VQVo8IU7rxXKSnZ7F30=
 github.com/mholt/acmez v1.2.0/go.mod h1:VT9YwH1xgNX1kmYY89gY8xPJC84BFAisjo8Egigt4kE=
 github.com/mholt/archives v0.1.5 h1:Fh2hl1j7VEhc6DZs2DLMgiBNChUux154a1G+2esNvzQ=
diff --git a/pkg/catalog/index/filter.go b/pkg/catalog/index/filter.go
new file mode 100644
index 00000000..ac4959a5
--- /dev/null
+++ b/pkg/catalog/index/filter.go
@@ -0,0 +1,344 @@
+package index
+
+import (
+	"path/filepath"
+	"slices"
+	"strings"
+
+	"github.com/projectdiscovery/nuclei/v3/pkg/model/types/severity"
+	"github.com/projectdiscovery/nuclei/v3/pkg/templates/types"
+)
+
+// Filter represents filtering criteria for template metadata.
+//
+// Inclusion fields (e.g., Authors, Tags, IDs, Severities, ProtocolTypes) use
+// AND logic across different filter types and OR logic within each type.
+// Exclusion fields (e.g., ExcludeTags, ExcludeIDs, ExcludeSeverities,
+// ExcludeProtocolTypes) take precedence over inclusion fields. Additionally,
+// IncludeTemplates and IncludeTags can force inclusion of templates even if
+// they match exclusion criteria.
+type Filter struct {
+	// Authors to include.
+	Authors []string
+
+	// Tags to include.
+	Tags []string
+
+	// ExcludeTags to exclude (takes precedence over Tags).
+	ExcludeTags []string
+
+	// IncludeTags to force include even if excluded.
+	IncludeTags []string
+
+	// IDs to include (supports wildcards, OR logic).
+	IDs []string
+
+	// ExcludeIDs to exclude (supports wildcards).
+	ExcludeIDs []string
+
+	// IncludeTemplates paths to force include even if excluded.
+	IncludeTemplates []string
+
+	// ExcludeTemplates paths to exclude.
+	ExcludeTemplates []string
+
+	// Severities to include.
+	Severities []severity.Severity
+
+	// ExcludeSeverities to exclude.
+	ExcludeSeverities []severity.Severity
+
+	// ProtocolTypes to include.
+	ProtocolTypes []types.ProtocolType
+
+	// ExcludeProtocolTypes to exclude.
+	ExcludeProtocolTypes []types.ProtocolType
+}
+
+// Matches checks if metadata matches the filter criteria.
+func (f *Filter) Matches(m *Metadata) bool {
+	if f.isForcedInclude(m) {
+		return true
+	}
+
+	if f.isExcluded(m) {
+		return false
+	}
+
+	if !f.matchesIncludes(m) {
+		return false
+	}
+
+	return true
+}
+
+// isForcedInclude checks if template is forced to be included.
+func (f *Filter) isForcedInclude(m *Metadata) bool {
+	if len(f.IncludeTemplates) > 0 {
+		for _, includePath := range f.IncludeTemplates {
+			if matchesPath(m.FilePath, includePath) {
+				return true
+			}
+		}
+	}
+
+	if len(f.IncludeTags) > 0 {
+		if slices.ContainsFunc(f.IncludeTags, m.HasTag) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// isExcluded checks if template should be excluded.
+func (f *Filter) isExcluded(m *Metadata) bool {
+	if len(f.ExcludeTemplates) > 0 {
+		for _, excludePath := range f.ExcludeTemplates {
+			if matchesPath(m.FilePath, excludePath) {
+				return true
+			}
+		}
+	}
+
+	if len(f.ExcludeTags) > 0 {
+		if slices.ContainsFunc(f.ExcludeTags, m.HasTag) {
+			return true
+		}
+	}
+
+	if len(f.ExcludeIDs) > 0 {
+		for _, excludeID := range f.ExcludeIDs {
+			if matchesID(m.ID, excludeID) {
+				return true
+			}
+		}
+	}
+
+	if len(f.ExcludeSeverities) > 0 {
+		if slices.ContainsFunc(f.ExcludeSeverities, m.MatchesSeverity) {
+			return true
+		}
+	}
+
+	if len(f.ExcludeProtocolTypes) > 0 {
+		if slices.ContainsFunc(f.ExcludeProtocolTypes, m.MatchesProtocol) {
+			return true
+		}
+	}
+
+	return false
+}
+
+// matchesIncludes checks if metadata matches include filters.
+//
+// Returns true if no include filters are specified, or if all specified filter
+// types match.
+func (f *Filter) matchesIncludes(m *Metadata) bool {
+	if len(f.Authors) > 0 {
+		if !slices.ContainsFunc(f.Authors, m.HasAuthor) {
+			return false
+		}
+	}
+
+	if len(f.Tags) > 0 {
+		if !slices.ContainsFunc(f.Tags, m.HasTag) {
+			return false
+		}
+	}
+
+	if len(f.IDs) > 0 {
+		matched := false
+		for _, id := range f.IDs {
+			if matchesID(m.ID, id) {
+				matched = true
+				break
+			}
+		}
+		if !matched {
+			return false
+		}
+	}
+
+	if len(f.Severities) > 0 {
+		if !slices.ContainsFunc(f.Severities, m.MatchesSeverity) {
+			return false
+		}
+	}
+
+	if len(f.ProtocolTypes) > 0 {
+		if !slices.ContainsFunc(f.ProtocolTypes, m.MatchesProtocol) {
+			return false
+		}
+	}
+
+	return true
+}
+
+// matchesID checks if template ID matches pattern (supports wildcards).
+func matchesID(templateID, pattern string) bool {
+	// Convert to lowercase for case-insensitive matching
+	templateID = strings.ToLower(templateID)
+	pattern = strings.ToLower(pattern)
+
+	if templateID == pattern {
+		return true
+	}
+
+	matched, _ := filepath.Match(pattern, templateID)
+
+	return matched
+}
+
+// matchesPath checks if template path matches pattern.
+func matchesPath(templatePath, pattern string) bool {
+	templatePath = filepath.Clean(templatePath)
+	pattern = filepath.Clean(pattern)
+
+	if templatePath == pattern {
+		return true
+	}
+
+	if strings.HasPrefix(templatePath, pattern+string(filepath.Separator)) {
+		return true
+	}
+
+	matched, _ := filepath.Match(pattern, templatePath)
+
+	return matched
+}
+
+// FilterFunc is a function that filters metadata.
+type FilterFunc func(*Metadata) bool
+
+// UnmarshalFilter creates a Filter from nuclei options.
+func UnmarshalFilter(
+	authors, tags, excludeTags, includeTags []string,
+	ids, excludeIDs []string,
+	includeTemplates, excludeTemplates []string,
+	severities, excludeSeverities []string,
+	protocolTypes, excludeProtocolTypes []string,
+) (*Filter, error) {
+	filter := &Filter{
+		Authors:          authors,
+		Tags:             tags,
+		ExcludeTags:      excludeTags,
+		IncludeTags:      includeTags,
+		IDs:              ids,
+		ExcludeIDs:       excludeIDs,
+		IncludeTemplates: includeTemplates,
+		ExcludeTemplates: excludeTemplates,
+	}
+
+	for _, sev := range severities {
+		holder := &severity.Holder{}
+		if err := holder.UnmarshalYAML(func(v interface{}) error {
+			*v.(*string) = sev
+			return nil
+		}); err == nil {
+			filter.Severities = append(filter.Severities, holder.Severity)
+		}
+	}
+
+	for _, sev := range excludeSeverities {
+		holder := &severity.Holder{}
+		if err := holder.UnmarshalYAML(func(v interface{}) error {
+			*v.(*string) = sev
+			return nil
+		}); err == nil {
+			filter.ExcludeSeverities = append(filter.ExcludeSeverities, holder.Severity)
+		}
+	}
+
+	for _, pt := range protocolTypes {
+		holder := &types.TypeHolder{}
+		if err := holder.UnmarshalYAML(func(v interface{}) error {
+			*v.(*string) = pt
+			return nil
+		}); err == nil && holder.ProtocolType != types.InvalidProtocol {
+			filter.ProtocolTypes = append(filter.ProtocolTypes, holder.ProtocolType)
+		}
+	}
+
+	for _, pt := range excludeProtocolTypes {
+		holder := &types.TypeHolder{}
+		if err := holder.UnmarshalYAML(func(v interface{}) error {
+			*v.(*string) = pt
+			return nil
+		}); err == nil && holder.ProtocolType != types.InvalidProtocol {
+			filter.ExcludeProtocolTypes = append(filter.ExcludeProtocolTypes, holder.ProtocolType)
+		}
+	}
+
+	return filter, nil
+}
+
+// UnmarshalFilterFunc creates a FilterFunc from filter criteria.
+func UnmarshalFilterFunc(filter *Filter) FilterFunc {
+	if filter == nil {
+		return func(*Metadata) bool { return true }
+	}
+
+	return filter.Matches
+}
+
+// IsEmpty returns true if filter has no criteria set.
+func (f *Filter) IsEmpty() bool {
+	return len(f.Authors) == 0 &&
+		len(f.Tags) == 0 &&
+		len(f.ExcludeTags) == 0 &&
+		len(f.IncludeTags) == 0 &&
+		len(f.IDs) == 0 &&
+		len(f.ExcludeIDs) == 0 &&
+		len(f.IncludeTemplates) == 0 &&
+		len(f.ExcludeTemplates) == 0 &&
+		len(f.Severities) == 0 &&
+		len(f.ExcludeSeverities) == 0 &&
+		len(f.ProtocolTypes) == 0 &&
+		len(f.ExcludeProtocolTypes) == 0
+}
+
+// String returns a human-readable representation of the filter.
+func (f *Filter) String() string {
+	var parts []string
+
+	if len(f.Authors) > 0 {
+		parts = append(parts, "authors="+strings.Join(f.Authors, ","))
+	}
+
+	if len(f.Tags) > 0 {
+		parts = append(parts, "tags="+strings.Join(f.Tags, ","))
+	}
+
+	if len(f.ExcludeTags) > 0 {
+		parts = append(parts, "exclude-tags="+strings.Join(f.ExcludeTags, ","))
+	}
+
+	if len(f.IDs) > 0 {
+		parts = append(parts, "ids="+strings.Join(f.IDs, ","))
+	}
+
+	if len(f.Severities) > 0 {
+		sevs := make([]string, len(f.Severities))
+		for i, s := range f.Severities {
+			sevs[i] = s.String()
+		}
+
+		parts = append(parts, "severities="+strings.Join(sevs, ","))
+	}
+
+	if len(f.ProtocolTypes) > 0 {
+		pts := make([]string, len(f.ProtocolTypes))
+		for i, p := range f.ProtocolTypes {
+			pts[i] = p.String()
+		}
+
+		parts = append(parts, "types="+strings.Join(pts, ","))
+	}
+
+	if len(parts) == 0 {
+		return "filter=<nil>"
+	}
+
+	return "filter(" + strings.Join(parts, ", ") + ")"
+}
diff --git a/pkg/catalog/index/index.go b/pkg/catalog/index/index.go
new file mode 100644
index 00000000..3024851b
--- /dev/null
+++ b/pkg/catalog/index/index.go
@@ -0,0 +1,352 @@
+package index
+
+import (
+	"encoding/gob"
+	"maps"
+	"os"
+	"path/filepath"
+	"sync"
+
+	"github.com/maypok86/otter/v2"
+	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/config"
+	"github.com/projectdiscovery/nuclei/v3/pkg/templates"
+	folderutil "github.com/projectdiscovery/utils/folder"
+)
+
+const (
+	// IndexFileName is the name of the persistent cache file.
+	IndexFileName = "index.gob"
+
+	// IndexVersion is the schema version for cache invalidation on breaking
+	// changes.
+	IndexVersion = 1
+
+	// DefaultMaxSize is the default maximum number of templates to cache.
+	DefaultMaxSize = 50000
+
+	// DefaultMaxWeight is the default maximum weight of the cache.
+	DefaultMaxWeight = DefaultMaxSize * 800 // ~40MB assuming ~800B/entry
+)
+
+// Index represents a cache for template metadata.
+type Index struct {
+	cache     *otter.Cache[string, *Metadata]
+	cacheFile string
+	mu        sync.RWMutex
+	version   int
+}
+
+// cacheSnapshot represents the serialized cache structure.
+type cacheSnapshot struct {
+	Version int                  `gob:"version"`
+	Data    map[string]*Metadata `gob:"data"`
+}
+
+// NewIndex creates a new template metadata cache with the given options.
+func NewIndex(cacheDir string) (*Index, error) {
+	if cacheDir == "" {
+		cacheDir = folderutil.AppCacheDirOrDefault(".nuclei-cache", config.BinaryName)
+	}
+
+	if err := os.MkdirAll(cacheDir, 0755); err != nil {
+		return nil, err
+	}
+
+	cacheFile := filepath.Join(cacheDir, IndexFileName)
+
+	// NOTE(dwisiswant0): Build cache with adaptive sizing based on memory cost.
+	opts := &otter.Options[string, *Metadata]{
+		MaximumWeight: uint64(DefaultMaxWeight),
+		Weigher: func(key string, value *Metadata) uint32 {
+			if value == nil {
+				return uint32(len(key))
+			}
+
+			weight := len(key)
+			weight += len(value.ID)
+			weight += len(value.FilePath)
+			weight += 24 // ModTime is time.Time (24B)
+			weight += len(value.Name)
+			weight += len(value.Severity)
+			weight += len(value.ProtocolType)
+			weight += len(value.TemplateVerifier)
+
+			for _, author := range value.Authors {
+				weight += len(author)
+			}
+			for _, tag := range value.Tags {
+				weight += len(tag)
+			}
+
+			return uint32(weight)
+		},
+	}
+
+	cache, err := otter.New(opts)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &Index{
+		cache:     cache,
+		cacheFile: cacheFile,
+		version:   IndexVersion,
+	}
+
+	return c, nil
+}
+
+// NewDefaultIndex creates a index with default settings in the default cache
+// directory.
+func NewDefaultIndex() (*Index, error) {
+	return NewIndex("")
+}
+
+// Get retrieves metadata for a template path, validating freshness via mtime.
+func (i *Index) Get(path string) (*Metadata, bool) {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	metadata, found := i.cache.GetIfPresent(path)
+	if !found {
+		return nil, false
+	}
+
+	if !metadata.IsValid() {
+		go i.Delete(path)
+
+		return nil, false
+	}
+
+	return metadata, true
+}
+
+// Set stores metadata for a template path.
+//
+// The caller is responsible for ensuring the metadata is valid and contains
+// the correct checksum before calling this method.
+// Use [SetFromTemplate] for automatic extraction and checksum computation.
+//
+// Returns the metadata and whether it was successfully cached (false if evicted).
+func (i *Index) Set(path string, metadata *Metadata) (*Metadata, bool) {
+	i.mu.Lock()
+	defer i.mu.Unlock()
+
+	return i.cache.Set(path, metadata)
+}
+
+// SetFromTemplate extracts metadata from a parsed template and stores it.
+//
+// Returns the metadata and whether it was successfully cached. The metadata is
+// always returned (even on checksum failure) for immediate filtering use.
+// Returns false if the metadata was not cached (e.g., set, evicted).
+func (i *Index) SetFromTemplate(path string, tpl *templates.Template) (*Metadata, bool) {
+	metadata := NewMetadataFromTemplate(path, tpl)
+
+	info, err := os.Stat(path)
+	if err != nil {
+		return metadata, false
+	}
+	metadata.ModTime = info.ModTime()
+
+	if i.cache == nil {
+		return metadata, false
+	}
+
+	return i.Set(path, metadata)
+}
+
+// Has checks if metadata exists for a path without validation.
+func (i *Index) Has(path string) bool {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	_, found := i.cache.GetIfPresent(path)
+
+	return found
+}
+
+// Delete removes metadata for a path.
+func (i *Index) Delete(path string) {
+	i.mu.Lock()
+	defer i.mu.Unlock()
+
+	i.cache.Invalidate(path)
+}
+
+// Size returns the number of cached entries.
+func (i *Index) Size() int {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	return i.cache.EstimatedSize()
+}
+
+// Clear removes all cached entries.
+func (i *Index) Clear() {
+	i.mu.Lock()
+	defer i.mu.Unlock()
+
+	i.cache.InvalidateAll()
+}
+
+// Save persists the cache to disk using gob encoding.
+func (i *Index) Save() error {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	snapshot := &cacheSnapshot{
+		Version: i.version,
+		Data:    make(map[string]*Metadata),
+	}
+
+	maps.Insert(snapshot.Data, i.cache.All())
+
+	// NOTE(dwisiswant0): write to temp for atomic op.
+	tmpFile := i.cacheFile + ".tmp"
+	file, err := os.Create(tmpFile)
+	if err != nil {
+		return err
+	}
+
+	encoder := gob.NewEncoder(file)
+	if err := encoder.Encode(snapshot); err != nil {
+		_ = file.Close()
+		_ = os.Remove(tmpFile)
+
+		return err
+	}
+
+	if err := file.Close(); err != nil {
+		_ = os.Remove(tmpFile)
+
+		return err
+	}
+
+	if err := os.Rename(tmpFile, i.cacheFile); err != nil {
+		_ = os.Remove(tmpFile)
+
+		return err
+	}
+
+	return nil
+}
+
+// Load loads the cache from disk using gob decoding.
+func (i *Index) Load() error {
+	file, err := os.Open(i.cacheFile)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil
+		}
+
+		return err
+	}
+	defer func() { _ = file.Close() }()
+
+	var snapshot cacheSnapshot
+
+	decoder := gob.NewDecoder(file)
+	if err := decoder.Decode(&snapshot); err != nil {
+		_ = file.Close()
+		_ = os.Remove(i.cacheFile)
+
+		return nil
+	}
+
+	if snapshot.Version != i.version {
+		_ = file.Close()
+		_ = os.Remove(i.cacheFile)
+
+		return nil
+	}
+
+	i.mu.Lock()
+	defer i.mu.Unlock()
+
+	for key, value := range snapshot.Data {
+		i.cache.Set(key, value)
+	}
+
+	return nil
+}
+
+// Filter returns all template paths that match the given filter criteria.
+func (i *Index) Filter(filter *Filter) []string {
+	if filter == nil || filter.IsEmpty() {
+		return i.All()
+	}
+
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	var matched []string
+	for path, metadata := range i.cache.All() {
+		if filter.Matches(metadata) {
+			matched = append(matched, path)
+		}
+	}
+
+	return matched
+}
+
+// FilterFunc returns all template paths that match the given filter function.
+func (i *Index) FilterFunc(fn FilterFunc) []string {
+	if fn == nil {
+		return i.All()
+	}
+
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	var matched []string
+	for path, metadata := range i.cache.All() {
+		if fn(metadata) {
+			matched = append(matched, path)
+		}
+	}
+
+	return matched
+}
+
+// All returns all template paths in the index.
+func (i *Index) All() []string {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	paths := make([]string, 0, i.cache.EstimatedSize())
+	for path := range i.cache.All() {
+		paths = append(paths, path)
+	}
+
+	return paths
+}
+
+// GetAll returns all metadata entries in the index.
+func (i *Index) GetAll() map[string]*Metadata {
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	result := maps.Collect(i.cache.All())
+
+	return result
+}
+
+// Count returns the number of templates matching the filter.
+func (i *Index) Count(filter *Filter) int {
+	if filter == nil || filter.IsEmpty() {
+		return i.Size()
+	}
+
+	i.mu.RLock()
+	defer i.mu.RUnlock()
+
+	count := 0
+	for _, metadata := range i.cache.All() {
+		if filter.Matches(metadata) {
+			count++
+		}
+	}
+
+	return count
+}
diff --git a/pkg/catalog/index/metadata.go b/pkg/catalog/index/metadata.go
new file mode 100644
index 00000000..013ab439
--- /dev/null
+++ b/pkg/catalog/index/metadata.go
@@ -0,0 +1,104 @@
+package index
+
+import (
+	"os"
+	"slices"
+	"time"
+
+	"github.com/projectdiscovery/nuclei/v3/pkg/model/types/severity"
+	"github.com/projectdiscovery/nuclei/v3/pkg/templates"
+	"github.com/projectdiscovery/nuclei/v3/pkg/templates/types"
+)
+
+// Metadata contains lightweight metadata extracted from a template.
+type Metadata struct {
+	// ID is the unique identifier of the template.
+	ID string `gob:"id"`
+
+	// FilePath is the path to the template file.
+	FilePath string `gob:"file_path"`
+
+	// ModTime is the modification time of the template file.
+	ModTime time.Time `gob:"mod_time"`
+
+	// Name is the name of the template.
+	Name string `gob:"name"`
+
+	// Authors are the authors of the template.
+	Authors []string `gob:"authors"`
+
+	// Tags are the tags associated with the template.
+	Tags []string `gob:"tags"`
+
+	// Severity is the severity level of the template.
+	Severity string `gob:"severity"`
+
+	// ProtocolType is the primary protocol type of the template.
+	ProtocolType string `gob:"protocol_type"`
+
+	// Verified indicates whether the template is verified.
+	Verified bool `gob:"verified"`
+
+	// TemplateVerifier is the verifier used for the template.
+	TemplateVerifier string `gob:"verifier,omitempty"`
+
+	// NOTE(dwisiswant0): Consider adding more fields here in the future to
+	// enhance filtering caps w/o loading full templates, such as:
+	// `has_{code,headless,file}` to indicate presence of protocol-based
+	// requests, and/or classification fields (CVE, CWE, CVSS, EPSS), if needed.
+	//
+	// For maintainers: when adding new fields, don't forget to update the
+	// Weigher logic in [NewIndex] to account for the new fields in cache weight
+	// calculation, because it affects cache eviction behavior. Also, consider
+	// the impact on existing cached data and whether a [IndexVersion] bump is
+	// needed.
+}
+
+// NewMetadataFromTemplate creates a new metadata object from a template.
+func NewMetadataFromTemplate(path string, tpl *templates.Template) *Metadata {
+	return &Metadata{
+		ID:       tpl.ID,
+		FilePath: path,
+
+		Name:     tpl.Info.Name,
+		Authors:  tpl.Info.Authors.ToSlice(),
+		Tags:     tpl.Info.Tags.ToSlice(),
+		Severity: tpl.Info.SeverityHolder.Severity.String(),
+
+		ProtocolType: tpl.Type().String(),
+
+		Verified:         tpl.Verified,
+		TemplateVerifier: tpl.TemplateVerifier,
+	}
+}
+
+// IsValid checks if the cached metadata is still valid by comparing the file
+// modification time.
+func (m *Metadata) IsValid() bool {
+	info, err := os.Stat(m.FilePath)
+	if err != nil {
+		return false
+	}
+
+	return m.ModTime.Equal(info.ModTime())
+}
+
+// MatchesSeverity checks if the metadata matches the given severity.
+func (m *Metadata) MatchesSeverity(sev severity.Severity) bool {
+	return m.Severity == sev.String()
+}
+
+// MatchesProtocol checks if the metadata matches the given protocol type.
+func (m *Metadata) MatchesProtocol(protocolType types.ProtocolType) bool {
+	return m.ProtocolType == protocolType.String()
+}
+
+// HasTag checks if the metadata contains the given tag.
+func (m *Metadata) HasTag(tag string) bool {
+	return slices.Contains(m.Tags, tag)
+}
+
+// HasAuthor checks if the metadata contains the given author.
+func (m *Metadata) HasAuthor(author string) bool {
+	return slices.Contains(m.Authors, author)
+}
diff --git a/pkg/catalog/loader/loader.go b/pkg/catalog/loader/loader.go
index a68153d8..00bc970b 100644
--- a/pkg/catalog/loader/loader.go
+++ b/pkg/catalog/loader/loader.go
@@ -14,7 +14,7 @@ import (
 	"github.com/projectdiscovery/gologger"
 	"github.com/projectdiscovery/nuclei/v3/pkg/catalog"
 	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/config"
-	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/loader/filter"
+	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/index"
 	"github.com/projectdiscovery/nuclei/v3/pkg/keys"
 	"github.com/projectdiscovery/nuclei/v3/pkg/model/types/severity"
 	"github.com/projectdiscovery/nuclei/v3/pkg/protocols"
@@ -77,7 +77,6 @@ type Config struct {
 type Store struct {
 	id             string // id of the store (optional)
 	tagFilter      *templates.TagFilter
-	pathFilter     *filter.PathFilter
 	config         *Config
 	finalTemplates []string
 	finalWorkflows []string
@@ -92,6 +91,16 @@ type Store struct {
 	// parserCacheOnce is used to cache the parser cache result
 	parserCacheOnce func() *templates.Cache
 
+	// metadataIndex is the template metadata cache
+	metadataIndex *index.Index
+
+	// indexFilter is the cached filter for metadata matching
+	indexFilter *index.Filter
+
+	// saveTemplatesIndexOnce is used to ensure we only save the metadata index
+	// once
+	saveMetadataIndexOnce func()
+
 	// NotFoundCallback is called for each not found template
 	// This overrides error handling for not found templates
 	NotFoundCallback func(template string) bool
@@ -129,17 +138,10 @@ func NewConfig(options *types.Options, catalog catalog.Catalog, executerOpts *pr
 
 // New creates a new template store based on provided configuration
 func New(cfg *Config) (*Store, error) {
+	// tagFilter only for IncludeConditions (advanced filtering).
+	// All other filtering (tags, authors, severities, IDs, protocols, paths) is
+	// handled by [index.Filter].
 	tagFilter, err := templates.NewTagFilter(&templates.TagFilterConfig{
-		Tags:              cfg.Tags,
-		ExcludeTags:       cfg.ExcludeTags,
-		Authors:           cfg.Authors,
-		Severities:        cfg.Severities,
-		ExcludeSeverities: cfg.ExcludeSeverities,
-		IncludeTags:       cfg.IncludeTags,
-		IncludeIds:        cfg.IncludeIds,
-		ExcludeIds:        cfg.ExcludeIds,
-		Protocols:         cfg.Protocols,
-		ExcludeProtocols:  cfg.ExcludeProtocols,
 		IncludeConditions: cfg.IncludeConditions,
 	})
 	if err != nil {
@@ -147,13 +149,9 @@ func New(cfg *Config) (*Store, error) {
 	}
 
 	store := &Store{
-		id:        cfg.StoreId,
-		config:    cfg,
-		tagFilter: tagFilter,
-		pathFilter: filter.NewPathFilter(&filter.PathFilterConfig{
-			IncludedTemplates: cfg.IncludeTemplates,
-			ExcludedTemplates: cfg.ExcludeTemplates,
-		}, cfg.Catalog),
+		id:             cfg.StoreId,
+		config:         cfg,
+		tagFilter:      tagFilter,
 		finalTemplates: cfg.Templates,
 		finalWorkflows: cfg.Workflows,
 		logger:         cfg.Logger,
@@ -171,6 +169,21 @@ func New(cfg *Config) (*Store, error) {
 		return nil
 	})
 
+	// Initialize metadata index and filter (load from disk & cache for reuse)
+	store.metadataIndex = store.loadTemplatesIndex()
+	store.indexFilter = store.buildIndexFilter()
+	store.saveMetadataIndexOnce = sync.OnceFunc(func() {
+		if store.metadataIndex == nil {
+			return
+		}
+
+		if err := store.metadataIndex.Save(); err != nil {
+			store.logger.Warning().Msgf("Could not save metadata cache: %v", err)
+		} else {
+			store.logger.Verbose().Msgf("Saved %d templates to metadata cache", store.metadataIndex.Size())
+		}
+	})
+
 	// Do a check to see if we have URLs in templates flag, if so
 	// we need to processs them separately and remove them from the initial list
 	var templatesFinal []string
@@ -302,17 +315,102 @@ func init() {
 	templateIDPathMap = make(map[string]string)
 }
 
+// buildIndexFilter creates an [index.Filter] from the store configuration.
+// This filter handles all basic filtering (paths, tags, authors, severities,
+// IDs, protocols). Advanced IncludeConditions filtering is handled separately
+// by tagFilter.
+func (store *Store) buildIndexFilter() *index.Filter {
+	includeTemplates, _ := store.config.Catalog.GetTemplatesPath(store.config.IncludeTemplates)
+	excludeTemplates, _ := store.config.Catalog.GetTemplatesPath(store.config.ExcludeTemplates)
+
+	return &index.Filter{
+		Authors:              store.config.Authors,
+		Tags:                 store.config.Tags,
+		ExcludeTags:          store.config.ExcludeTags,
+		IncludeTags:          store.config.IncludeTags,
+		IDs:                  store.config.IncludeIds,
+		ExcludeIDs:           store.config.ExcludeIds,
+		IncludeTemplates:     includeTemplates,
+		ExcludeTemplates:     excludeTemplates,
+		Severities:           []severity.Severity(store.config.Severities),
+		ExcludeSeverities:    []severity.Severity(store.config.ExcludeSeverities),
+		ProtocolTypes:        []templateTypes.ProtocolType(store.config.Protocols),
+		ExcludeProtocolTypes: []templateTypes.ProtocolType(store.config.ExcludeProtocols),
+	}
+}
+
+func (store *Store) loadTemplatesIndex() *index.Index {
+	var metadataIdx *index.Index
+
+	idx, err := index.NewDefaultIndex()
+	if err != nil {
+		store.logger.Warning().Msgf("Could not create metadata cache: %v", err)
+	} else {
+		metadataIdx = idx
+		if err := metadataIdx.Load(); err != nil {
+			store.logger.Warning().Msgf("Could not load metadata cache: %v", err)
+		}
+	}
+
+	return metadataIdx
+}
+
 // LoadTemplatesOnlyMetadata loads only the metadata of the templates
 func (store *Store) LoadTemplatesOnlyMetadata() error {
+	defer store.saveMetadataIndexOnce()
+
 	templatePaths, errs := store.config.Catalog.GetTemplatesPath(store.finalTemplates)
 	store.logErroredTemplates(errs)
 
-	filteredTemplatePaths := store.pathFilter.Match(templatePaths)
-
+	indexFilter := store.indexFilter
 	validPaths := make(map[string]struct{})
-	for templatePath := range filteredTemplatePaths {
+
+	for _, templatePath := range templatePaths {
+		if store.metadataIndex != nil {
+			if metadata, found := store.metadataIndex.Get(templatePath); found {
+				if !indexFilter.Matches(metadata) {
+					continue
+				}
+
+				if store.tagFilter != nil {
+					loaded, err := store.config.ExecutorOptions.Parser.LoadTemplate(templatePath, store.tagFilter, nil, store.config.Catalog)
+					if !loaded {
+						if err != nil && strings.Contains(err.Error(), templates.ErrExcluded.Error()) {
+							stats.Increment(templates.TemplatesExcludedStats)
+							if config.DefaultConfig.LogAllEvents {
+								store.logger.Print().Msgf("[%v] %v\n", aurora.Yellow("WRN").String(), err.Error())
+							}
+						}
+						continue
+					}
+				}
+
+				validPaths[templatePath] = struct{}{}
+				continue
+			}
+		}
+
 		loaded, err := store.config.ExecutorOptions.Parser.LoadTemplate(templatePath, store.tagFilter, nil, store.config.Catalog)
-		if loaded || store.pathFilter.MatchIncluded(templatePath) {
+		if loaded {
+			templatesCache := store.parserCacheOnce()
+			if templatesCache != nil {
+				if template, _, _ := templatesCache.Has(templatePath); template != nil {
+					var metadata *index.Metadata
+					if store.metadataIndex != nil {
+						metadata, _ = store.metadataIndex.SetFromTemplate(templatePath, template)
+					} else {
+						metadata = index.NewMetadataFromTemplate(templatePath, template)
+					}
+
+					if !indexFilter.Matches(metadata) {
+						continue
+					}
+
+					validPaths[templatePath] = struct{}{}
+					continue
+				}
+			}
+
 			validPaths[templatePath] = struct{}{}
 		}
 		if err != nil {
@@ -376,15 +474,24 @@ func (store *Store) LoadTemplatesOnlyMetadata() error {
 func (store *Store) ValidateTemplates() error {
 	templatePaths, errs := store.config.Catalog.GetTemplatesPath(store.finalTemplates)
 	store.logErroredTemplates(errs)
+
 	workflowPaths, errs := store.config.Catalog.GetTemplatesPath(store.finalWorkflows)
 	store.logErroredTemplates(errs)
 
-	filteredTemplatePaths := store.pathFilter.Match(templatePaths)
-	filteredWorkflowPaths := store.pathFilter.Match(workflowPaths)
+	templatePathsMap := make(map[string]struct{}, len(templatePaths))
+	for _, path := range templatePaths {
+		templatePathsMap[path] = struct{}{}
+	}
+
+	workflowPathsMap := make(map[string]struct{}, len(workflowPaths))
+	for _, path := range workflowPaths {
+		workflowPathsMap[path] = struct{}{}
+	}
 
-	if store.areTemplatesValid(filteredTemplatePaths) && store.areWorkflowsValid(filteredWorkflowPaths) {
+	if store.areTemplatesValid(templatePathsMap) && store.areWorkflowsValid(workflowPathsMap) {
 		return nil
 	}
+
 	return errors.New("errors occurred during template validation")
 }
 
@@ -503,10 +610,9 @@ func (store *Store) LoadTemplates(templatesList []string) []*templates.Template
 func (store *Store) LoadWorkflows(workflowsList []string) []*templates.Template {
 	includedWorkflows, errs := store.config.Catalog.GetTemplatesPath(workflowsList)
 	store.logErroredTemplates(errs)
-	workflowPathMap := store.pathFilter.Match(includedWorkflows)
 
-	loadedWorkflows := make([]*templates.Template, 0, len(workflowPathMap))
-	for workflowPath := range workflowPathMap {
+	loadedWorkflows := make([]*templates.Template, 0, len(includedWorkflows))
+	for _, workflowPath := range includedWorkflows {
 		loaded, err := store.config.ExecutorOptions.Parser.LoadWorkflow(workflowPath, store.config.Catalog)
 		if err != nil {
 			store.logger.Warning().Msgf("Could not load workflow %s: %s\n", workflowPath, err)
@@ -526,9 +632,12 @@ func (store *Store) LoadWorkflows(workflowsList []string) []*templates.Template
 // LoadTemplatesWithTags takes a list of templates and extra tags
 // returning templates that match.
 func (store *Store) LoadTemplatesWithTags(templatesList, tags []string) []*templates.Template {
+	defer store.saveMetadataIndexOnce()
+
+	indexFilter := store.indexFilter
+
 	includedTemplates, errs := store.config.Catalog.GetTemplatesPath(templatesList)
 	store.logErroredTemplates(errs)
-	templatePathMap := store.pathFilter.Match(includedTemplates)
 
 	loadedTemplates := sliceutil.NewSyncSlice[*templates.Template]()
 	loadedTemplateIDs := mapsutil.NewSyncLockMap[string, struct{}]()
@@ -572,14 +681,46 @@ func (store *Store) LoadTemplatesWithTags(templatesList, tags []string) []*templ
 		panic("dialers with executionId " + store.config.ExecutorOptions.Options.ExecutionId + " not found")
 	}
 
-	for templatePath := range templatePathMap {
+	for _, templatePath := range includedTemplates {
 		wgLoadTemplates.Add()
 		go func(templatePath string) {
 			defer wgLoadTemplates.Done()
 
+			var (
+				metadata       *index.Metadata
+				metadataCached bool
+			)
+
+			if store.metadataIndex != nil {
+				if cachedMetadata, found := store.metadataIndex.Get(templatePath); found {
+					metadata = cachedMetadata
+					if !indexFilter.Matches(metadata) {
+						return
+					}
+					// NOTE(dwisiswant0): else, tagFilter probably exists (for
+					// IncludeConditions), which still need to check via
+					// LoadTemplate.
+
+					metadataCached = true
+				}
+			}
+
 			loaded, err := store.config.ExecutorOptions.Parser.LoadTemplate(templatePath, store.tagFilter, tags, store.config.Catalog)
-			if loaded || store.pathFilter.MatchIncluded(templatePath) {
+			if loaded {
 				parsed, err := templates.Parse(templatePath, store.preprocessor, store.config.ExecutorOptions)
+
+				if parsed != nil && !metadataCached {
+					if store.metadataIndex != nil {
+						metadata, _ = store.metadataIndex.SetFromTemplate(templatePath, parsed)
+					} else {
+						metadata = index.NewMetadataFromTemplate(templatePath, parsed)
+					}
+
+					if metadata != nil && !indexFilter.Matches(metadata) {
+						return
+					}
+				}
+
 				if err != nil {
 					// exclude templates not compatible with offline matching from total runtime warning stats
 					if !errors.Is(err, templates.ErrIncompatibleWithOfflineMatching) {



Test patch:
diff --git a/cmd/integration-test/library.go b/cmd/integration-test/library.go
index 3513b1d0..2c4cda57 100644
--- a/cmd/integration-test/library.go
+++ b/cmd/integration-test/library.go
@@ -15,6 +15,7 @@ import (
 	"github.com/logrusorgru/aurora"
 	"github.com/pkg/errors"
 	"github.com/projectdiscovery/goflags"
+	"github.com/projectdiscovery/gologger"
 	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/config"
 	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/disk"
 	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/loader"
@@ -70,6 +71,7 @@ func executeNucleiAsLibrary(templatePath, templateURL string) ([]string, error)
 
 	defaultOpts := types.DefaultOptions()
 	defaultOpts.ExecutionId = "test"
+	defaultOpts.Logger = gologger.DefaultLogger
 
 	mockProgress := &testutils.MockProgressClient{}
 	reportingClient, err := reporting.New(&reporting.Options{ExecutionId: defaultOpts.ExecutionId}, "", false)
diff --git a/pkg/catalog/index/filter_test.go b/pkg/catalog/index/filter_test.go
new file mode 100644
index 00000000..2bc4735e
--- /dev/null
+++ b/pkg/catalog/index/filter_test.go
@@ -0,0 +1,407 @@
+package index
+
+import (
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/projectdiscovery/nuclei/v3/pkg/model/types/severity"
+	"github.com/projectdiscovery/nuclei/v3/pkg/templates/types"
+	"github.com/stretchr/testify/require"
+)
+
+func TestFilterMatches(t *testing.T) {
+	metadata := &Metadata{
+		ID:           "test-template-1",
+		FilePath:     "/templates/cves/2021/CVE-2021-1234.yaml",
+		Name:         "Test CVE Template",
+		Authors:      []string{"pdteam", "geeknik"},
+		Tags:         []string{"cve", "rce", "apache"},
+		Severity:     "critical",
+		ProtocolType: "http",
+	}
+
+	t.Run("Empty filter matches all", func(t *testing.T) {
+		filter := &Filter{}
+		require.True(t, filter.Matches(metadata))
+		require.True(t, filter.IsEmpty())
+	})
+
+	t.Run("Author filter - match", func(t *testing.T) {
+		filter := &Filter{Authors: []string{"pdteam"}}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("Author filter - no match", func(t *testing.T) {
+		filter := &Filter{Authors: []string{"unknown"}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Multiple authors - OR logic", func(t *testing.T) {
+		filter := &Filter{Authors: []string{"unknown", "geeknik"}}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("Tag filter - match", func(t *testing.T) {
+		filter := &Filter{Tags: []string{"cve"}}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("Tag filter - no match", func(t *testing.T) {
+		filter := &Filter{Tags: []string{"xss"}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Exclude tags - match", func(t *testing.T) {
+		filter := &Filter{ExcludeTags: []string{"rce"}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Include tags overrides exclude", func(t *testing.T) {
+		filter := &Filter{
+			ExcludeTags: []string{"rce"},
+			IncludeTags: []string{"cve"},
+		}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("ID filter - exact match", func(t *testing.T) {
+		filter := &Filter{IDs: []string{"test-template-1"}}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("ID filter - wildcard match", func(t *testing.T) {
+		filter := &Filter{IDs: []string{"test-*"}}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("ID filter - no match", func(t *testing.T) {
+		filter := &Filter{IDs: []string{"other-*"}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Exclude ID - exact match", func(t *testing.T) {
+		filter := &Filter{ExcludeIDs: []string{"test-template-1"}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Exclude ID - wildcard match", func(t *testing.T) {
+		filter := &Filter{ExcludeIDs: []string{"test-*"}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Severity filter - match", func(t *testing.T) {
+		filter := &Filter{Severities: []severity.Severity{severity.Critical}}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("Severity filter - no match", func(t *testing.T) {
+		filter := &Filter{Severities: []severity.Severity{severity.High, severity.Medium}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Exclude severity - match", func(t *testing.T) {
+		filter := &Filter{ExcludeSeverities: []severity.Severity{severity.Critical}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Protocol type filter - match", func(t *testing.T) {
+		filter := &Filter{ProtocolTypes: []types.ProtocolType{types.HTTPProtocol}}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("Protocol type filter - no match", func(t *testing.T) {
+		filter := &Filter{ProtocolTypes: []types.ProtocolType{types.DNSProtocol}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Exclude protocol type - match", func(t *testing.T) {
+		filter := &Filter{ExcludeProtocolTypes: []types.ProtocolType{types.HTTPProtocol}}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Include templates - path match", func(t *testing.T) {
+		filter := &Filter{
+			ExcludeTags:      []string{"cve"},
+			IncludeTemplates: []string{"/templates/cves/"},
+		}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("Exclude templates - path match", func(t *testing.T) {
+		filter := &Filter{
+			ExcludeTemplates: []string{"/templates/cves/"},
+		}
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Complex filter - all match", func(t *testing.T) {
+		filter := &Filter{
+			Authors:       []string{"pdteam"},
+			Tags:          []string{"cve"},
+			Severities:    []severity.Severity{severity.Critical},
+			ProtocolTypes: []types.ProtocolType{types.HTTPProtocol},
+		}
+		require.True(t, filter.Matches(metadata))
+	})
+
+	t.Run("Complex filter - AND logic across types", func(t *testing.T) {
+		filter := &Filter{
+			Authors:    []string{"pdteam"},                     // matches
+			Tags:       []string{"xss"},                        // doesn't match
+			Severities: []severity.Severity{severity.Critical}, // matches
+		}
+		// With AND logic across filter types, doesn't match because tags don't match
+		// even though author and severity match
+		require.False(t, filter.Matches(metadata))
+	})
+
+	t.Run("Complex filter - no match at all", func(t *testing.T) {
+		filter := &Filter{
+			Authors:    []string{"unknown"},               // doesn't match
+			Tags:       []string{"xss"},                   // doesn't match
+			Severities: []severity.Severity{severity.Low}, // doesn't match
+		}
+		require.False(t, filter.Matches(metadata))
+	})
+}
+
+func TestMatchesPath(t *testing.T) {
+	tests := []struct {
+		name     string
+		path     string
+		pattern  string
+		expected bool
+	}{
+		{"exact match", "/templates/cves/2021/test.yaml", "/templates/cves/2021/test.yaml", true},
+		{"directory prefix", "/templates/cves/2021/test.yaml", "/templates/cves", true},
+		{"directory with slash", "/templates/cves/2021/test.yaml", "/templates/cves/", true},
+		{"no match", "/templates/cves/2021/test.yaml", "/templates/exploits", false},
+		{"wildcard match", "/templates/cves/2021/test.yaml", "/templates/*/2021/*.yaml", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := matchesPath(tt.path, tt.pattern)
+			require.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestMatchesID(t *testing.T) {
+	tests := []struct {
+		name     string
+		id       string
+		pattern  string
+		expected bool
+	}{
+		{"exact match", "CVE-2021-1234", "CVE-2021-1234", true},
+		{"wildcard prefix", "CVE-2021-1234", "CVE-*", true},
+		{"wildcard suffix", "CVE-2021-1234", "*-1234", true},
+		{"wildcard middle", "CVE-2021-1234", "CVE-*-1234", true},
+		{"no match", "CVE-2021-1234", "CVE-2022-*", false},
+		{"partial no match", "CVE-2021-1234", "CVE-2021-12", false},
+		{"case insensitive exact", "cve-2021-1234", "CVE-2021-1234", true},
+		{"case insensitive wildcard", "CVE-2021-1234", "cve-*", true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := matchesID(tt.id, tt.pattern)
+			require.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+func TestUnmarshalFilter(t *testing.T) {
+	filter, err := UnmarshalFilter(
+		[]string{"author1", "author2"},
+		[]string{"tag1", "tag2"},
+		[]string{"exclude-tag"},
+		[]string{"include-tag"},
+		[]string{"id1", "id2*"},
+		[]string{"exclude-id*"},
+		[]string{"/include/path"},
+		[]string{"/exclude/path"},
+		[]string{"critical", "high"},
+		[]string{"info"},
+		[]string{"http", "dns"},
+		[]string{"file"},
+	)
+
+	require.NoError(t, err)
+	require.NotNil(t, filter)
+
+	require.Equal(t, []string{"author1", "author2"}, filter.Authors)
+	require.Equal(t, []string{"tag1", "tag2"}, filter.Tags)
+	require.Equal(t, []string{"exclude-tag"}, filter.ExcludeTags)
+	require.Equal(t, []string{"include-tag"}, filter.IncludeTags)
+	require.Equal(t, []string{"id1", "id2*"}, filter.IDs)
+	require.Equal(t, []string{"exclude-id*"}, filter.ExcludeIDs)
+	require.Equal(t, []string{"/include/path"}, filter.IncludeTemplates)
+	require.Equal(t, []string{"/exclude/path"}, filter.ExcludeTemplates)
+
+	require.Len(t, filter.Severities, 2)
+	require.Contains(t, filter.Severities, severity.Critical)
+	require.Contains(t, filter.Severities, severity.High)
+
+	require.Len(t, filter.ExcludeSeverities, 1)
+	require.Contains(t, filter.ExcludeSeverities, severity.Info)
+
+	require.Len(t, filter.ProtocolTypes, 2)
+	require.Contains(t, filter.ProtocolTypes, types.HTTPProtocol)
+	require.Contains(t, filter.ProtocolTypes, types.DNSProtocol)
+
+	require.Len(t, filter.ExcludeProtocolTypes, 1)
+	require.Contains(t, filter.ExcludeProtocolTypes, types.FileProtocol)
+}
+
+func TestIndexFilter(t *testing.T) {
+	tmpDir := t.TempDir()
+	idx, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	// Create test templates and metadata
+	templates := []struct {
+		id       string
+		path     string
+		authors  []string
+		tags     []string
+		severity string
+		protocol string
+	}{
+		{"cve-2021-1", "/templates/cves/CVE-2021-1.yaml", []string{"pdteam"}, []string{"cve", "rce"}, "critical", "http"},
+		{"cve-2021-2", "/templates/cves/CVE-2021-2.yaml", []string{"pdteam"}, []string{"cve", "xss"}, "high", "http"},
+		{"exploit-1", "/templates/exploits/exploit-1.yaml", []string{"geeknik"}, []string{"exploit"}, "medium", "dns"},
+		{"info-1", "/templates/info/info-1.yaml", []string{"author1"}, []string{"info"}, "info", "http"},
+	}
+
+	for _, tmpl := range templates {
+		tmpFile := filepath.Join(tmpDir, filepath.Base(tmpl.path))
+		err := os.WriteFile(tmpFile, []byte("id: "+tmpl.id), 0644)
+		require.NoError(t, err)
+
+		metadata := &Metadata{
+			ID:           tmpl.id,
+			FilePath:     tmpFile,
+			Authors:      tmpl.authors,
+			Tags:         tmpl.tags,
+			Severity:     tmpl.severity,
+			ProtocolType: tmpl.protocol,
+		}
+		idx.Set(tmpl.path, metadata)
+	}
+
+	t.Run("No filter returns all", func(t *testing.T) {
+		results := idx.Filter(nil)
+		require.Len(t, results, 4)
+	})
+
+	t.Run("Filter by author", func(t *testing.T) {
+		filter := &Filter{Authors: []string{"pdteam"}}
+		results := idx.Filter(filter)
+		require.Len(t, results, 2)
+	})
+
+	t.Run("Filter by tag", func(t *testing.T) {
+		filter := &Filter{Tags: []string{"cve"}}
+		results := idx.Filter(filter)
+		require.Len(t, results, 2)
+	})
+
+	t.Run("Filter by severity", func(t *testing.T) {
+		filter := &Filter{Severities: []severity.Severity{severity.Critical}}
+		results := idx.Filter(filter)
+		require.Len(t, results, 1)
+	})
+
+	t.Run("Filter by protocol type", func(t *testing.T) {
+		filter := &Filter{ProtocolTypes: []types.ProtocolType{types.HTTPProtocol}}
+		results := idx.Filter(filter)
+		require.Len(t, results, 3)
+	})
+
+	t.Run("Exclude by severity", func(t *testing.T) {
+		filter := &Filter{ExcludeSeverities: []severity.Severity{severity.Info}}
+		results := idx.Filter(filter)
+		require.Len(t, results, 3)
+	})
+
+	t.Run("Exclude by tag", func(t *testing.T) {
+		filter := &Filter{ExcludeTags: []string{"info"}}
+		results := idx.Filter(filter)
+		require.Len(t, results, 3)
+	})
+
+	t.Run("Complex filter", func(t *testing.T) {
+		filter := &Filter{
+			Tags:              []string{"cve"},
+			Severities:        []severity.Severity{severity.Critical, severity.High},
+			ExcludeSeverities: []severity.Severity{severity.Info},
+		}
+		results := idx.Filter(filter)
+		require.Len(t, results, 2)
+	})
+
+	t.Run("Count with filter", func(t *testing.T) {
+		filter := &Filter{Tags: []string{"cve"}}
+		count := idx.Count(filter)
+		require.Equal(t, 2, count)
+	})
+
+	t.Run("Count without filter", func(t *testing.T) {
+		count := idx.Count(nil)
+		require.Equal(t, 4, count)
+	})
+}
+
+func TestIndexFilterFunc(t *testing.T) {
+	tmpDir := t.TempDir()
+	idx, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	// Add test metadata
+	for i := 0; i < 5; i++ {
+		metadata := &Metadata{
+			ID:       "test-" + string(rune('a'+i)),
+			FilePath: "/tmp/test.yaml",
+			Severity: "high",
+		}
+		if i%2 == 0 {
+			metadata.Tags = []string{"even"}
+		} else {
+			metadata.Tags = []string{"odd"}
+		}
+		idx.Set("/tmp/test-"+string(rune('a'+i))+".yaml", metadata)
+	}
+
+	t.Run("Custom filter function", func(t *testing.T) {
+		results := idx.FilterFunc(func(m *Metadata) bool {
+			return m.HasTag("even")
+		})
+		require.Len(t, results, 3) // 0, 2, 4
+	})
+
+	t.Run("Nil filter function returns all", func(t *testing.T) {
+		results := idx.FilterFunc(nil)
+		require.Len(t, results, 5)
+	})
+}
+
+func TestFilterString(t *testing.T) {
+	filter := &Filter{
+		Authors:       []string{"author1", "author2"},
+		Tags:          []string{"tag1"},
+		Severities:    []severity.Severity{severity.Critical, severity.High},
+		ProtocolTypes: []types.ProtocolType{types.HTTPProtocol},
+	}
+
+	str := filter.String()
+	require.Contains(t, str, "authors=")
+	require.Contains(t, str, "tags=")
+	require.Contains(t, str, "severities=")
+	require.Contains(t, str, "types=")
+
+	emptyFilter := &Filter{}
+	require.Equal(t, "filter=<nil>", emptyFilter.String())
+}
diff --git a/pkg/catalog/index/index_test.go b/pkg/catalog/index/index_test.go
new file mode 100644
index 00000000..de76dd75
--- /dev/null
+++ b/pkg/catalog/index/index_test.go
@@ -0,0 +1,737 @@
+package index
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/projectdiscovery/nuclei/v3/pkg/model"
+	"github.com/projectdiscovery/nuclei/v3/pkg/model/types/severity"
+	"github.com/projectdiscovery/nuclei/v3/pkg/model/types/stringslice"
+	"github.com/projectdiscovery/nuclei/v3/pkg/protocols/code"
+	"github.com/projectdiscovery/nuclei/v3/pkg/protocols/headless"
+	"github.com/projectdiscovery/nuclei/v3/pkg/protocols/http"
+	"github.com/projectdiscovery/nuclei/v3/pkg/templates"
+	"github.com/projectdiscovery/nuclei/v3/pkg/templates/types"
+	"github.com/stretchr/testify/require"
+)
+
+func TestNewIndex(t *testing.T) {
+	t.Run("with custom directory", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		cache, err := NewIndex(tmpDir)
+		require.NoError(t, err, "Failed to create cache with custom directory")
+		require.NotNil(t, cache, "Cache should not be nil")
+		require.Equal(t, filepath.Join(tmpDir, IndexFileName), cache.cacheFile)
+		require.Equal(t, IndexVersion, cache.version)
+	})
+
+	t.Run("with default directory", func(t *testing.T) {
+		cache, err := NewDefaultIndex()
+		require.NoError(t, err, "Failed to create cache with default directory")
+		require.NotNil(t, cache, "Cache should not be nil")
+	})
+}
+
+func TestCacheBasicOperations(t *testing.T) {
+	tmpDir := t.TempDir()
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	metadata := &Metadata{
+		ID:       "concurrent-test",
+		FilePath: "/tmp/concurrent.yaml",
+	}
+
+	t.Run("Set and Has", func(t *testing.T) {
+		cache.Set(metadata.FilePath, metadata)
+		require.Equal(t, 1, cache.Size(), "Cache size should be 1 after Set")
+		require.True(t, cache.Has(metadata.FilePath), "Cache should contain the path after Set")
+		require.False(t, cache.Has("/nonexistent"), "Cache should not contain nonexistent path")
+	})
+
+	t.Run("Get with validation", func(t *testing.T) {
+		// Get should fail validation for nonexistent file
+		retrieved, found := cache.Get(metadata.FilePath)
+		require.False(t, found, "Get should fail validation for nonexistent file")
+		require.Nil(t, retrieved, "Retrieved metadata should be nil for invalid entry")
+	})
+
+	t.Run("Delete", func(t *testing.T) {
+		cache.Set(metadata.FilePath, metadata)
+		require.True(t, cache.Has(metadata.FilePath), "Cache should contain path before Delete")
+
+		cache.Delete(metadata.FilePath)
+		require.False(t, cache.Has(metadata.FilePath), "Cache should not contain path after Delete")
+	})
+
+	t.Run("Clear", func(t *testing.T) {
+		cache.Set(metadata.FilePath, metadata)
+		cache.Set("/tmp/test2.yaml", &Metadata{ID: "test2", FilePath: "/tmp/test2.yaml"})
+		require.True(t, cache.Size() > 0, "Cache should have entries before Clear")
+
+		cache.Clear()
+		require.Equal(t, 0, cache.Size(), "Cache should be empty after Clear")
+	})
+}
+
+func TestCachePersistence(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	metadata1 := &Metadata{
+		ID:           "persist-test-1",
+		FilePath:     "/tmp/persist1.yaml",
+		Name:         "Persistence Test 1",
+		Authors:      []string{"tester"},
+		Tags:         []string{"test"},
+		Severity:     "medium",
+		ProtocolType: "dns",
+	}
+
+	metadata2 := &Metadata{
+		ID:           "persist-test-2",
+		FilePath:     "/tmp/persist2.yaml",
+		Name:         "Persistence Test 2",
+		Authors:      []string{"tester2"},
+		Tags:         []string{"cve"},
+		Severity:     "critical",
+		ProtocolType: "http",
+	}
+
+	t.Run("Save and Load", func(t *testing.T) {
+		// Create cache and add entries
+		cache1, err := NewIndex(tmpDir)
+		require.NoError(t, err)
+
+		cache1.Set(metadata1.FilePath, metadata1)
+		cache1.Set(metadata2.FilePath, metadata2)
+		require.Equal(t, 2, cache1.Size())
+
+		// Save to disk
+		err = cache1.Save()
+		require.NoError(t, err, "Failed to save cache")
+
+		// Verify cache file exists
+		cacheFile := filepath.Join(tmpDir, IndexFileName)
+		stat, err := os.Stat(cacheFile)
+		require.NoError(t, err, "Cache file should exist")
+		require.Greater(t, stat.Size(), int64(0), "Cache file should not be empty")
+
+		// Create new cache and load
+		cache2, err := NewIndex(tmpDir)
+		require.NoError(t, err)
+		require.Equal(t, 0, cache2.Size(), "New cache should be empty before Load")
+
+		err = cache2.Load()
+		require.NoError(t, err, "Failed to load cache")
+
+		// Verify data was loaded
+		require.Equal(t, 2, cache2.Size(), "Loaded cache should have 2 entries")
+		require.True(t, cache2.Has(metadata1.FilePath), "Loaded cache should contain first entry")
+		require.True(t, cache2.Has(metadata2.FilePath), "Loaded cache should contain second entry")
+	})
+
+	t.Run("Load non-existent cache", func(t *testing.T) {
+		emptyDir := t.TempDir()
+		cache, err := NewIndex(emptyDir)
+		require.NoError(t, err)
+
+		// Loading non-existent cache should not error
+		err = cache.Load()
+		require.NoError(t, err, "Loading non-existent cache should not error")
+		require.Equal(t, 0, cache.Size(), "Cache should be empty after loading non-existent file")
+	})
+
+	t.Run("Atomic save", func(t *testing.T) {
+		cache, err := NewIndex(tmpDir)
+		require.NoError(t, err)
+
+		cache.Set(metadata1.FilePath, metadata1)
+		err = cache.Save()
+		require.NoError(t, err)
+
+		// Verify no .tmp file left behind
+		tmpFile := filepath.Join(tmpDir, IndexFileName+".tmp")
+		_, err = os.Stat(tmpFile)
+		require.True(t, os.IsNotExist(err), "Temporary file should not exist after save")
+
+		// Verify actual cache file exists
+		cacheFile := filepath.Join(tmpDir, IndexFileName)
+		_, err = os.Stat(cacheFile)
+		require.NoError(t, err, "Cache file should exist")
+	})
+}
+
+func TestIndexVersionMismatch(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	// Create cache with current version
+	cache1, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	metadata := &Metadata{
+		ID:       "version-test",
+		FilePath: "/tmp/version.yaml",
+	}
+	cache1.Set(metadata.FilePath, metadata)
+
+	// Save with current version
+	err = cache1.Save()
+	require.NoError(t, err)
+
+	// Manually modify version and save again
+	cache1.version = 999
+	err = cache1.Save()
+	require.NoError(t, err)
+
+	// Try to load with different version
+	cache2, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	// Load should succeed but cache should be empty (version mismatch)
+	err = cache2.Load()
+	require.NoError(t, err, "Load should not error on version mismatch")
+	require.Equal(t, 0, cache2.Size(), "Cache should be empty after version mismatch")
+}
+
+func TestCacheCorruptedFile(t *testing.T) {
+	tmpDir := t.TempDir()
+	cacheFile := filepath.Join(tmpDir, IndexFileName)
+
+	// Create corrupted cache file
+	err := os.WriteFile(cacheFile, []byte("corrupted data that is not valid gob"), 0644)
+	require.NoError(t, err)
+
+	// Try to load corrupted cache
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	err = cache.Load()
+	require.NoError(t, err, "Load should not error on corrupted cache")
+	require.Equal(t, 0, cache.Size(), "Cache should be empty after loading corrupted file")
+
+	// Corrupted file should be removed
+	_, err = os.Stat(cacheFile)
+	require.True(t, os.IsNotExist(err), "Corrupted cache file should be removed")
+}
+
+func TestMetadataValidation(t *testing.T) {
+	tmpDir := t.TempDir()
+	tmpFile := filepath.Join(tmpDir, "test.yaml")
+
+	t.Run("Valid metadata", func(t *testing.T) {
+		// Create a test file
+		err := os.WriteFile(tmpFile, []byte("id: test\ninfo:\n  name: Test"), 0644)
+		require.NoError(t, err)
+
+		info, err := os.Stat(tmpFile)
+		require.NoError(t, err)
+
+		// Create metadata with correct checksum
+		metadata := &Metadata{
+			ID:       "test",
+			FilePath: tmpFile,
+			ModTime:  info.ModTime(),
+		}
+
+		// Should be valid
+		require.True(t, metadata.IsValid(), "Metadata should be valid for unchanged file")
+	})
+
+	t.Run("Invalid metadata after file modification", func(t *testing.T) {
+		// Create the test file first to ensure it exists in this subtest
+		err := os.WriteFile(tmpFile, []byte("id: test\ninfo:\n  name: Test"), 0644)
+		require.NoError(t, err)
+
+		// Set file ModTime to past to ensure modification is detectable
+		oldTime := time.Now().Add(-2 * time.Second)
+		err = os.Chtimes(tmpFile, oldTime, oldTime)
+		require.NoError(t, err)
+
+		info, err := os.Stat(tmpFile)
+		require.NoError(t, err)
+
+		metadata := &Metadata{
+			ID:       "test",
+			FilePath: tmpFile,
+			ModTime:  info.ModTime(),
+		}
+
+		// Modify file
+		err = os.WriteFile(tmpFile, []byte("id: test\ninfo:\n  name: Modified"), 0644)
+		require.NoError(t, err)
+
+		// Should now be invalid
+		require.False(t, metadata.IsValid(), "Metadata should be invalid after file modification")
+	})
+
+	t.Run("Invalid metadata for deleted file", func(t *testing.T) {
+		// Create the test file first to ensure it exists in this subtest
+		err := os.WriteFile(tmpFile, []byte("id: test\ninfo:\n  name: Test"), 0644)
+		require.NoError(t, err)
+
+		info, err := os.Stat(tmpFile)
+		require.NoError(t, err)
+
+		metadata := &Metadata{
+			ID:       "test",
+			FilePath: tmpFile,
+			ModTime:  info.ModTime(),
+		}
+
+		// Delete file
+		err = os.Remove(tmpFile)
+		require.NoError(t, err)
+
+		// Should be invalid
+		require.False(t, metadata.IsValid(), "Metadata should be invalid for deleted file")
+	})
+}
+
+func TestSetFromTemplate(t *testing.T) {
+	tmpDir := t.TempDir()
+	tmpFile := filepath.Join(tmpDir, "extract.yaml")
+
+	// Create a test file
+	err := os.WriteFile(tmpFile, []byte("id: extract-test"), 0644)
+	require.NoError(t, err)
+
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	t.Run("Basic metadata extraction", func(t *testing.T) {
+		template := &templates.Template{
+			ID: "extract-test",
+			Info: model.Info{
+				Name:        "Extract Test Template",
+				Authors:     stringslice.StringSlice{Value: "author1,author2"},
+				Tags:        stringslice.StringSlice{Value: "tag1,tag2"},
+				Description: "Test description",
+				SeverityHolder: severity.Holder{
+					Severity: severity.High,
+				},
+			},
+			SelfContained:    true,
+			Verified:         true,
+			TemplateVerifier: "test-verifier",
+		}
+
+		metadata, ok := cache.SetFromTemplate(tmpFile, template)
+		require.True(t, ok, "Failed to set metadata from template")
+		require.NotNil(t, metadata, "Metadata should not be nil")
+
+		// Verify core fields
+		require.Equal(t, "extract-test", metadata.ID)
+		require.Equal(t, tmpFile, metadata.FilePath)
+
+		// Verify Info fields
+		require.Equal(t, "Extract Test Template", metadata.Name)
+		require.Equal(t, []string{"author1,author2"}, metadata.Authors)
+		require.Equal(t, []string{"tag1,tag2"}, metadata.Tags)
+		require.Equal(t, "high", metadata.Severity)
+
+		// Verify flags
+		require.True(t, metadata.Verified)
+		require.Equal(t, "test-verifier", metadata.TemplateVerifier)
+	})
+
+	t.Run("HTTP protocol detection", func(t *testing.T) {
+		// Create a separate test file for this test
+		httpFile := filepath.Join(tmpDir, "http-test.yaml")
+		err := os.WriteFile(httpFile, []byte("id: http-test"), 0644)
+		require.NoError(t, err)
+
+		template := &templates.Template{
+			ID: "http-test",
+			Info: model.Info{
+				Name:    "HTTP Test",
+				Authors: stringslice.StringSlice{Value: "tester"},
+				SeverityHolder: severity.Holder{
+					Severity: severity.Medium,
+				},
+			},
+			RequestsHTTP: []*http.Request{{Method: http.HTTPMethodTypeHolder{MethodType: http.HTTPGet}}},
+		}
+
+		metadata, ok := cache.SetFromTemplate(httpFile, template)
+		require.True(t, ok)
+		require.NotNil(t, metadata)
+		require.Equal(t, "http", metadata.ProtocolType)
+	})
+
+	t.Run("Extract with missing file", func(t *testing.T) {
+		template := &templates.Template{
+			ID: "missing-test",
+			Info: model.Info{
+				Name:    "Missing File Test",
+				Authors: stringslice.StringSlice{Value: "tester"},
+				SeverityHolder: severity.Holder{
+					Severity: severity.Low,
+				},
+			},
+		}
+
+		metadata, ok := cache.SetFromTemplate("/nonexistent/file.yaml", template)
+		require.False(t, ok, "Should return false for nonexistent file")
+		require.NotNil(t, metadata, "Metadata should still be returned")
+	})
+}
+
+func TestMetadataMatchingHelpers(t *testing.T) {
+	metadata := &Metadata{
+		Tags:         []string{"cve", "rce", "apache"},
+		Authors:      []string{"pdteam", "geeknik"},
+		Severity:     "critical",
+		ProtocolType: "http",
+	}
+
+	t.Run("HasTag", func(t *testing.T) {
+		require.True(t, metadata.HasTag("cve"))
+		require.True(t, metadata.HasTag("rce"))
+		require.True(t, metadata.HasTag("apache"))
+		require.False(t, metadata.HasTag("xxe"))
+		require.False(t, metadata.HasTag(""))
+	})
+
+	t.Run("HasAuthor", func(t *testing.T) {
+		require.True(t, metadata.HasAuthor("pdteam"))
+		require.True(t, metadata.HasAuthor("geeknik"))
+		require.False(t, metadata.HasAuthor("unknown"))
+		require.False(t, metadata.HasAuthor(""))
+	})
+
+	t.Run("MatchesSeverity", func(t *testing.T) {
+		require.True(t, metadata.MatchesSeverity(severity.Critical))
+		require.False(t, metadata.MatchesSeverity(severity.High))
+		require.False(t, metadata.MatchesSeverity(severity.Medium))
+		require.False(t, metadata.MatchesSeverity(severity.Low))
+		require.False(t, metadata.MatchesSeverity(severity.Info))
+	})
+
+	t.Run("MatchesProtocol", func(t *testing.T) {
+		require.True(t, metadata.MatchesProtocol(types.HTTPProtocol))
+		require.False(t, metadata.MatchesProtocol(types.DNSProtocol))
+		require.False(t, metadata.MatchesProtocol(types.FileProtocol))
+		require.False(t, metadata.MatchesProtocol(types.NetworkProtocol))
+	})
+
+	t.Run("Empty metadata", func(t *testing.T) {
+		emptyMetadata := &Metadata{}
+		require.False(t, emptyMetadata.HasTag("any"))
+		require.False(t, emptyMetadata.HasAuthor("any"))
+	})
+}
+
+func TestCacheConcurrency(t *testing.T) {
+	tmpDir := t.TempDir()
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	// Test concurrent writes
+	t.Run("Concurrent Set", func(t *testing.T) {
+		done := make(chan bool)
+		for i := 0; i < 10; i++ {
+			go func(id int) {
+				metadata := &Metadata{
+					ID:       string(rune('a' + id)),
+					FilePath: filepath.Join("/tmp", string(rune('a'+id))+".yaml"),
+				}
+				cache.Set(metadata.FilePath, metadata)
+				done <- true
+			}(i)
+		}
+
+		// Wait for all goroutines
+		for i := 0; i < 10; i++ {
+			<-done
+		}
+
+		require.Equal(t, 10, cache.Size(), "All concurrent writes should succeed")
+	})
+
+	// Test concurrent reads
+	t.Run("Concurrent Has", func(t *testing.T) {
+		metadata := &Metadata{
+			ID:       "concurrent-test",
+			FilePath: "/tmp/concurrent.yaml",
+		}
+		cache.Set(metadata.FilePath, metadata)
+
+		done := make(chan bool)
+		for i := 0; i < 20; i++ {
+			go func() {
+				_ = cache.Has(metadata.FilePath)
+				done <- true
+			}()
+		}
+
+		// Wait for all goroutines
+		for i := 0; i < 20; i++ {
+			<-done
+		}
+	})
+}
+
+func TestCacheSize(t *testing.T) {
+	tmpDir := t.TempDir()
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	require.Equal(t, 0, cache.Size(), "New cache should have size 0")
+
+	// Add entries
+	for i := 0; i < 5; i++ {
+		metadata := &Metadata{
+			ID:       string(rune('a' + i)),
+			FilePath: filepath.Join("/tmp", string(rune('a'+i))+".yaml"),
+		}
+		cache.Set(metadata.FilePath, metadata)
+	}
+
+	require.Equal(t, 5, cache.Size(), "Cache should have size 5 after adding 5 entries")
+
+	// Delete entries
+	cache.Delete(filepath.Join("/tmp", "a.yaml"))
+	cache.Delete(filepath.Join("/tmp", "b.yaml"))
+
+	require.Equal(t, 3, cache.Size(), "Cache should have size 3 after deleting 2 entries")
+
+	// Clear cache
+	cache.Clear()
+	require.Equal(t, 0, cache.Size(), "Cache should have size 0 after Clear")
+}
+
+func TestCacheGetWithValidFile(t *testing.T) {
+	tmpDir := t.TempDir()
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	// Create a real file for testing validation
+	tmpFile := filepath.Join(tmpDir, "test.yaml")
+	err = os.WriteFile(tmpFile, []byte("id: test"), 0644)
+	require.NoError(t, err)
+
+	info, err := os.Stat(tmpFile)
+	require.NoError(t, err)
+
+	metadata := &Metadata{
+		ID:       "test",
+		FilePath: tmpFile,
+		ModTime:  info.ModTime(),
+		Name:     "Test Template",
+	}
+
+	// Set and get should work with valid file
+	cache.Set(metadata.FilePath, metadata)
+	retrieved, found := cache.Get(metadata.FilePath)
+	require.True(t, found, "Should find entry with valid file")
+	require.NotNil(t, retrieved, "Retrieved metadata should not be nil")
+	require.Equal(t, metadata.ID, retrieved.ID)
+}
+
+func TestCacheSaveErrorHandling(t *testing.T) {
+	tmpDir := t.TempDir()
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	metadata := &Metadata{
+		ID:       "test",
+		FilePath: filepath.Join("/tmp", "test.yaml"),
+	}
+	cache.Set(metadata.FilePath, metadata)
+
+	// Create a directory where the temp file would be created to force an error
+	// The Save method creates a file at cacheFile + ".tmp"
+	conflictPath := filepath.Join(tmpDir, IndexFileName+".tmp")
+	err = os.Mkdir(conflictPath, 0755)
+	require.NoError(t, err)
+
+	err = cache.Save()
+	require.Error(t, err, "Save should fail when temp file cannot be created")
+}
+
+func TestNewCacheWithInvalidDirectory(t *testing.T) {
+	// Try to create cache in a file path (should fail)
+	tmpFile := filepath.Join(t.TempDir(), "file.txt")
+	err := os.WriteFile(tmpFile, []byte("test"), 0644)
+	require.NoError(t, err)
+
+	cache, err := NewIndex(tmpFile)
+	require.Error(t, err, "NewCache should fail when path is a file")
+	require.Nil(t, cache, "Cache should be nil on error")
+}
+
+func TestCacheLoadCorruptedRemoval(t *testing.T) {
+	tmpDir := t.TempDir()
+	cacheFile := filepath.Join(tmpDir, IndexFileName)
+
+	// Create corrupted cache file with invalid gob data
+	err := os.WriteFile(cacheFile, []byte("this is not valid gob encoding at all!"), 0644)
+	require.NoError(t, err)
+
+	// Verify file exists before Load
+	_, err = os.Stat(cacheFile)
+	require.NoError(t, err, "Corrupted file should exist")
+
+	// Load should not error but should remove corrupted file
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	err = cache.Load()
+	require.NoError(t, err, "Load should not return error for corrupted file")
+
+	// Verify corrupted file was removed
+	_, err = os.Stat(cacheFile)
+	require.True(t, os.IsNotExist(err), "Corrupted file should be removed")
+	require.Equal(t, 0, cache.Size(), "Cache should be empty after loading corrupted file")
+}
+
+func TestMetadataExtractionWithNilClassification(t *testing.T) {
+	tmpDir := t.TempDir()
+	tmpFile := filepath.Join(tmpDir, "test.yaml")
+	err := os.WriteFile(tmpFile, []byte("id: test"), 0644)
+	require.NoError(t, err)
+
+	template := &templates.Template{
+		ID: "nil-classification",
+		Info: model.Info{
+			Name:    "Template without classification",
+			Authors: stringslice.StringSlice{Value: "tester"},
+			SeverityHolder: severity.Holder{
+				Severity: severity.Medium,
+			},
+			Classification: nil, // Explicitly nil
+		},
+	}
+
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	metadata, ok := cache.SetFromTemplate(tmpFile, template)
+	require.True(t, ok)
+	require.NotNil(t, metadata)
+}
+
+func TestCachePersistenceWithLargeDataset(t *testing.T) {
+	tmpDir := t.TempDir()
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	// Add 100 entries to test bulk operations
+	for i := 0; i < 100; i++ {
+		metadata := &Metadata{
+			ID:       fmt.Sprintf("template-%d", i),
+			FilePath: filepath.Join("/tmp", fmt.Sprintf("template-%d.yaml", i)),
+			Name:     fmt.Sprintf("Template %d", i),
+			Authors:  []string{fmt.Sprintf("author%d", i)},
+			Tags:     []string{"tag1", "tag2", "tag3"},
+			Severity: "high",
+		}
+		cache.Set(metadata.FilePath, metadata)
+	}
+
+	require.Equal(t, 100, cache.Size(), "Cache should contain 100 entries")
+
+	// Save to disk
+	err = cache.Save()
+	require.NoError(t, err)
+
+	// Load into new cache
+	cache2, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+	err = cache2.Load()
+	require.NoError(t, err)
+
+	require.Equal(t, 100, cache2.Size(), "Loaded cache should contain 100 entries")
+
+	// Verify a sample entry
+	found := cache2.Has(filepath.Join("/tmp", "template-50.yaml"))
+	require.True(t, found, "Should find sample entry")
+}
+
+func TestMetadataHelperMethods(t *testing.T) {
+	metadata := &Metadata{
+		ID:           "helper-test",
+		Tags:         []string{},
+		Authors:      []string{},
+		Severity:     "",
+		ProtocolType: "",
+	}
+
+	t.Run("Empty tags", func(t *testing.T) {
+		require.False(t, metadata.HasTag("anytag"))
+	})
+
+	t.Run("Empty authors", func(t *testing.T) {
+		require.False(t, metadata.HasAuthor("anyauthor"))
+	})
+
+	t.Run("Empty severity", func(t *testing.T) {
+		require.False(t, metadata.MatchesSeverity(severity.Critical))
+	})
+
+	t.Run("Empty protocol", func(t *testing.T) {
+		require.False(t, metadata.MatchesProtocol(types.HTTPProtocol))
+	})
+}
+
+func TestMultipleProtocolsDetection(t *testing.T) {
+	tmpDir := t.TempDir()
+	tmpFile := filepath.Join(tmpDir, "multi.yaml")
+	err := os.WriteFile(tmpFile, []byte("id: multi"), 0644)
+	require.NoError(t, err)
+
+	// Template with multiple protocol types
+	template := &templates.Template{
+		ID: "multi-protocol",
+		Info: model.Info{
+			Name:    "Multi Protocol Template",
+			Authors: stringslice.StringSlice{Value: "tester"},
+			SeverityHolder: severity.Holder{
+				Severity: severity.High,
+			},
+		},
+		RequestsHTTP:     []*http.Request{{Method: http.HTTPMethodTypeHolder{MethodType: http.HTTPGet}}},
+		RequestsHeadless: []*headless.Request{{}},
+		RequestsCode:     []*code.Request{{}},
+	}
+
+	cache, err := NewIndex(tmpDir)
+	require.NoError(t, err)
+
+	metadata, ok := cache.SetFromTemplate(tmpFile, template)
+	require.True(t, ok)
+	require.NotNil(t, metadata)
+	require.Equal(t, "http", metadata.ProtocolType, "Primary protocol should be http")
+}
+
+func TestNewMetadataFromTemplate(t *testing.T) {
+	tmpl := &templates.Template{
+		ID: "test-template",
+		Info: model.Info{
+			Name:    "Test Template",
+			Authors: stringslice.StringSlice{Value: []string{"author"}},
+			Tags:    stringslice.StringSlice{Value: []string{"tag"}},
+			SeverityHolder: severity.Holder{
+				Severity: severity.Low,
+			},
+		},
+		Verified:         true,
+		TemplateVerifier: "verifier",
+	}
+
+	path := "/tmp/test.yaml"
+	metadata := NewMetadataFromTemplate(path, tmpl)
+
+	require.Equal(t, tmpl.ID, metadata.ID)
+	require.Equal(t, path, metadata.FilePath)
+	require.Equal(t, tmpl.Info.Name, metadata.Name)
+	require.Equal(t, tmpl.Info.Authors.ToSlice(), metadata.Authors)
+	require.Equal(t, tmpl.Info.Tags.ToSlice(), metadata.Tags)
+	require.Equal(t, tmpl.Info.SeverityHolder.Severity.String(), metadata.Severity)
+	require.Equal(t, tmpl.Type().String(), metadata.ProtocolType)
+	require.Equal(t, tmpl.Verified, metadata.Verified)
+	require.Equal(t, tmpl.TemplateVerifier, metadata.TemplateVerifier)
+}
diff --git a/pkg/catalog/loader/loader_bench_test.go b/pkg/catalog/loader/loader_bench_test.go
index 079e928a..32ed506e 100644
--- a/pkg/catalog/loader/loader_bench_test.go
+++ b/pkg/catalog/loader/loader_bench_test.go
@@ -8,7 +8,9 @@ import (
 	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/disk"
 	"github.com/projectdiscovery/nuclei/v3/pkg/catalog/loader"
 	"github.com/projectdiscovery/nuclei/v3/pkg/loader/workflow"
+	"github.com/projectdiscovery/nuclei/v3/pkg/model/types/severity"
 	"github.com/projectdiscovery/nuclei/v3/pkg/templates"
+	templateTypes "github.com/projectdiscovery/nuclei/v3/pkg/templates/types"
 	"github.com/projectdiscovery/nuclei/v3/pkg/testutils"
 )
 
@@ -41,3 +43,201 @@ func BenchmarkStoreValidateTemplates(b *testing.B) {
 		_ = store.ValidateTemplates()
 	}
 }
+
+func BenchmarkLoadTemplates(b *testing.B) {
+	options := testutils.DefaultOptions.Copy()
+	options.Logger = &gologger.Logger{}
+	options.ExecutionId = "bench-load-templates"
+	testutils.Init(options)
+
+	catalog := disk.NewCatalog(config.DefaultConfig.TemplatesDirectory)
+	executerOpts := testutils.NewMockExecuterOptions(options, nil)
+	executerOpts.Parser = templates.NewParser()
+
+	workflowLoader, err := workflow.NewLoader(executerOpts)
+	if err != nil {
+		b.Fatalf("could not create workflow loader: %s", err)
+	}
+	executerOpts.WorkflowLoader = workflowLoader
+
+	b.Run("NoFilter", func(b *testing.B) {
+		loaderCfg := loader.NewConfig(options, catalog, executerOpts)
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplates([]string{config.DefaultConfig.TemplatesDirectory})
+		}
+	})
+
+	b.Run("FilterBySeverityCritical", func(b *testing.B) {
+		opts := options.Copy()
+		opts.Severities = severity.Severities{severity.Critical}
+		loaderCfg := loader.NewConfig(opts, catalog, executerOpts)
+
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplates([]string{config.DefaultConfig.TemplatesDirectory})
+		}
+	})
+
+	b.Run("FilterBySeverityHighCritical", func(b *testing.B) {
+		opts := options.Copy()
+		opts.Severities = severity.Severities{severity.High, severity.Critical}
+		loaderCfg := loader.NewConfig(opts, catalog, executerOpts)
+
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplates([]string{config.DefaultConfig.TemplatesDirectory})
+		}
+	})
+
+	b.Run("FilterByAuthor", func(b *testing.B) {
+		opts := options.Copy()
+		opts.Authors = []string{"pdteam"}
+		loaderCfg := loader.NewConfig(opts, catalog, executerOpts)
+
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplates([]string{config.DefaultConfig.TemplatesDirectory})
+		}
+	})
+
+	b.Run("FilterByTags", func(b *testing.B) {
+		opts := options.Copy()
+		opts.Tags = []string{"cve", "rce"}
+		loaderCfg := loader.NewConfig(opts, catalog, executerOpts)
+
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplates([]string{config.DefaultConfig.TemplatesDirectory})
+		}
+	})
+
+	b.Run("FilterByProtocol", func(b *testing.B) {
+		opts := options.Copy()
+		opts.Protocols = templateTypes.ProtocolTypes{templateTypes.HTTPProtocol}
+		loaderCfg := loader.NewConfig(opts, catalog, executerOpts)
+
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplates([]string{config.DefaultConfig.TemplatesDirectory})
+		}
+	})
+
+	b.Run("ComplexFilter", func(b *testing.B) {
+		opts := options.Copy()
+		opts.Severities = severity.Severities{severity.High, severity.Critical}
+		opts.Authors = []string{"pdteam"}
+		opts.Tags = []string{"cve"}
+		loaderCfg := loader.NewConfig(opts, catalog, executerOpts)
+
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplates([]string{config.DefaultConfig.TemplatesDirectory})
+		}
+	})
+}
+
+func BenchmarkLoadTemplatesOnlyMetadata(b *testing.B) {
+	options := testutils.DefaultOptions.Copy()
+	options.Logger = &gologger.Logger{}
+	options.ExecutionId = "bench-metadata"
+	testutils.Init(options)
+
+	catalog := disk.NewCatalog(config.DefaultConfig.TemplatesDirectory)
+	executerOpts := testutils.NewMockExecuterOptions(options, nil)
+	executerOpts.Parser = templates.NewParser()
+
+	workflowLoader, err := workflow.NewLoader(executerOpts)
+	if err != nil {
+		b.Fatalf("could not create workflow loader: %s", err)
+	}
+	executerOpts.WorkflowLoader = workflowLoader
+
+	b.Run("WithoutFilter", func(b *testing.B) {
+		loaderCfg := loader.NewConfig(options, catalog, executerOpts)
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		// Pre-warm the cache
+		_ = store.LoadTemplatesOnlyMetadata()
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplatesOnlyMetadata()
+		}
+	})
+
+	b.Run("WithSeverityFilter", func(b *testing.B) {
+		opts := options.Copy()
+		opts.Severities = severity.Severities{severity.Critical}
+		loaderCfg := loader.NewConfig(opts, catalog, executerOpts)
+
+		store, err := loader.New(loaderCfg)
+		if err != nil {
+			b.Fatalf("could not create store: %s", err)
+		}
+
+		// Pre-warm the cache
+		_ = store.LoadTemplatesOnlyMetadata()
+
+		b.ResetTimer()
+		b.ReportAllocs()
+
+		for b.Loop() {
+			_ = store.LoadTemplatesOnlyMetadata()
+		}
+	})
+}