stom-resource)
      * [ Unity  ](/docs/app-check/unity/custom-resource)

    * [ Verify tokens on the backend  ](/docs/app-check/custom-resource-backend)

  * Extensions 

    * [ Introduction  ](/docs/extensions)
    * [ Use case examples  ](/docs/extensions/samples)
    * Use an extension in your project 

    * [ Overview  ](/docs/extensions/overview-use-extensions)
    * [ Install an extension  ](/docs/extensions/install-extensions)
    * [ Manage installed extensions  ](/docs/extensions/manage-installed-extensions)
    * [ Permissions granted to an extension  ](/docs/extensions/permissions-granted-to-extension)
    * [ Manage configurations with manifests  ](/docs/extensions/manifest)
    * Extensions by Firebase 

    * Trigger Email 

      * [ Get started  ](/docs/extensions/official/firestore-send-email)
      * [ Use Handlebars templates  ](/docs/extensions/official/firestore-send-email/templates)
      * [ Manage delivery status  ](/docs/extensions/official/firestore-send-email/delivery-status)

    * Delete User Data 

      * [ Get Started  ](/docs/extensions/official/delete-user-data)

    * Firestore Bundle Builder 

      * [ Get Started  ](/docs/extensions/official/firestore-bundle-builder)
      * [ Reference  ](/docs/extensions/official/firestore-bundle-builder/reference)

    * [ Resize Images  ](https://github.com/firebase/extensions/tree/master/storage-resize-images#resize-images)
    * [ Export Collections to BigQuery  ](https://github.com/firebase/extensions/tree/master/firestore-bigquery-export#export-collections-to-bigquery)
    * [ Translate Text  ](https://github.com/firebase/extensions/tree/master/firestore-translate-text#translate-text)
    * [ Distributed Counter  ](https://github.com/firebase/extensions/tree/master/firestore-counter#distributed-counter)
    * [ Shorten URLs  ](https://github.com/firebase/extensions/tree/master/firestore-shorten-urls-bitly#shorten-urls)
    * [ Limit Child Nodes  ](https://github.com/firebase/extensions/tree/master/rtdb-limit-child-nodes#limit-child-nodes)
    * Build & publish extensions 

    * [ Overview  ](/docs/extensions/publishers)
    * [ Get started  ](/docs/extensions/publishers/get-started)
    *     * [ Write functions  ](/docs/extensions/publishers/functions)
    * [ Set up parameters  ](/docs/extensions/publishers/parameters)
    * [ Handle lifecycle events  ](/docs/extensions/publishers/lifecycle-events)
    * [ Add user hooks  ](/docs/extensions/publishers/user-hooks)
    * [ Set up appropriate access  ](/docs/extensions/publishers/access)
    * [ Create user documentation  ](/docs/extensions/publishers/user-documentation)
    *     * [ Register as a publisher  ](/docs/extensions/publishers/register)
    * [ Publish an extension  ](/docs/extensions/publishers/upload-and-publish)
    *     * [ Reference for extension.yaml  ](/docs/extensions/reference/extension-yaml)
    *     * [ Firebase Extensions Publisher Agreement  ](/terms/extensions/publisher)

  * Related products 

  * [ Cloud Messaging  ](//firebase.google.com/docs/cloud-messaging/)
  * [ Remote Config  ](//firebase.google.com/docs/remote-config/)

  * [ Build  ](/products-build)
  * [ Release & Monitor  ](/products-release)
  * [ Engage  ](/products-engage)

  * [ Overview  ](/docs)
  * [ Fundamentals  ](/docs/guides)
  * [ Build  ](/docs/build)
  * [ Release & Monitor  ](/docs/release)
  * [ Engage  ](/docs/engage)
  * [ Reference  ](/docs/reference)
  * [ Samples  ](/docs/samples)

  * [ Learn  ](/community/learn)
  * [ Events  ](/community/events)
  * [ Stories  ](/community/stories)

  * [ Add Firebase - Apple platforms (iOS+)  ](/docs/ios/setup)
  * [ Add Firebase - Android  ](/docs/android/setup)
  * [ Add Firebase - Web  ](/docs/web/setup)
  * [ Add Firebase - Flutter  ](/docs/flutter/setup)
  * [ Add Firebase - C++  ](/docs/cpp/setup)
  * [ Add Firebase - Unity  ](/docs/unity/setup)
  * [ Add Firebase - Server environments  ](/docs/admin/setup)
  * [ Manage Firebase projects  ]