Best Practices when using API Designer | MuleSoft Documentation
# Best Practices when using API Designer
When you perform tasks on Design Center, you might encounter issues. Use the following topics to help you resolve them.
## API Designer Best Practices
  * Divide your fragments into short, reusable dependencies when possible.
  * Keep only one version of the same dependency.
  * Keep only one browser tab open at a time.


### API Designer Resources
When using API Designer, the required resources to parse the specification depend on the users own resources. For API Designer to function properly, ensure your computer has the following minimum resources available when using API Designer:
  * 8 GB RAM
  * Ryzen series 5 / Intel i5 CPU or higher


To achieve optimal parser performance, keep the total project size for all files in your design project below 500 KB.
A project size that exceeds 1.5 MB severely affects validation time.
### OAS Specification Best Practices
  * Use the `$ref` property to define reusable components. To improve parsing efficiency, reference each component from the API specification instead of duplicating component definitions, for example:
```
components:
 schemas:
  User:
   type: object
   properties:
    id:
     type: integer
paths:
 /users:
  get:
   responses:
    '200':
     description: Successful response
     content:
      application/json:
       schema:
        $ref: '#/components/schemas/User'
```

  * Use simpler types to represent your data if possible. Avoid unnecessary nesting and complicated types, for example:
```
properties:
 age:
  type: integer # Prefer simple types over complex types like objects
```

  * Use the `enum` property for fields with a fixed set of values to improve parsing efficiency:
```
properties:
 status:
  type: string
  enum: [active, inactive]
```

  * Use simple nesting for objects to simplify the structure and improve readability and parsing efficiency:
```
# Good
properties:
 name:
  type: string
 address:
  type: string
# Avoid
properties:
 user:
  type: object
  properties:
   profile:
    type: object
    properties:
     name:
      type: string
```

  * Use `response` headers instead of the response body to provide additional information, for example:
```
responses:
 '200':
  description: Successful response
  headers:
   X-Rate-Limit-Limit:
    description: The number of requests allowed in the current period
    schema:
     type: integer
```

  * Provide concise and short examples:
```
Book:
 type: string
 example: "Explain the string with as few words as possible."
```

  * When using union-type properties, use `oneOf` to represent union-type object fields, `allOf` to represent an intersection type and composite objects and fields, and `anyOf` when defining a property with multiple possible data structures.


### RAML Specification Best Practices
  * When extracting RAML fragments, import each fragment as a local declaration first:
Create a fragment file, and before publishing the fragment to Anypoint Exchange, import the local fragment file to validate that the fragment works as expected. If the fragment works, publish the fragment to Exchange so you can reuse the fragment in your API specifications instead of duplicating it.
  * Reuse data types as declarations.
  * Use inheritance only when needed:
```
Car:
 description: This is a car
 properties:
  brand: string
  model: string
 example:
  brand: Toyota
  model: Corolla
Person:
 properties:
  owns: Car
```

  * Use short unions:
```
Person:
 type: Employee | Customer
```

  * Use simple traits, and avoid combining traits with resource type properties:
```
/basic:
 type: {resourceTypes.fhirResourceType: {
   postExample : !include /examples/requests/post_resource.json,
   getExample : !include /examples/responses/get_resource.json,
   bundleName : basic.BasicBundle
  }
 }
 /_search:
  get:
   is: [ searchParams ]
  post:
   is: [ POSTSearchParams ]
```