Flagsmith Flags API

openapi: 3.1.0
info:
  title: Flagsmith Flags API
  description: >-
    The Flagsmith Flags API is the public-facing REST API that client-side and
    server-side SDKs use to retrieve feature flag values and remote
    configuration for environments and users. It uses a non-secret Environment
    Key for authentication and is designed to be fast, scalable, and publicly
    accessible. The Edge API endpoint at edge.api.flagsmith.com serves requests
    from AWS Lambda functions running in data centers near the client, providing
    low-latency global access to flag evaluations.
  version: '1.0'
  contact:
    name: Flagsmith Support
    url: https://www.flagsmith.com/contact-us
  termsOfService: https://www.flagsmith.com/terms-of-service
externalDocs:
  description: Flagsmith Flags API Documentation
  url: https://docs.flagsmith.com/clients/rest
servers:
  - url: https://edge.api.flagsmith.com/api/v1
    description: Flagsmith Edge API (SaaS)
  - url: https://api.flagsmith.com/api/v1
    description: Flagsmith Core API
tags:
  - name: Flags
    description: >-
      Retrieve feature flags for an environment. Returns the current state of
      all feature flags including their enabled status and values.
  - name: Identities
    description: >-
      Retrieve feature flags and traits for a specific user identity. Allows
      personalized flag evaluation based on user attributes and segment
      membership.
security:
  - environmentKey: []
paths:
  /flags/:
    get:
      operationId: listFlags
      summary: List all flags for an environment
      description: >-
        Retrieves all feature flags for the environment associated with the
        provided Environment Key. Returns an array of flag objects, each
        containing the feature definition, its enabled state, and any
        associated value. This endpoint is used by client-side SDKs to
        initialize flag state.
      tags:
        - Flags
      parameters:
        - $ref: '#/components/parameters/FeatureNameQuery'
      responses:
        '200':
          description: Successful response containing all flags for the environment
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Flag'
        '401':
          description: Unauthorized - invalid or missing Environment Key
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /identities/:
    get:
      operationId: getIdentityFlags
      summary: Get flags and traits for an identity
      description: >-
        Retrieves all feature flags and traits for a specific user identity.
        The flags returned may differ from the environment defaults based on
        the identity's traits and segment membership. If the identity does not
        exist, it will be created. This endpoint also supports transient
        identities and traits that are used for evaluation but not persisted.
      tags:
        - Identities
      parameters:
        - $ref: '#/components/parameters/IdentifierQuery'
        - $ref: '#/components/parameters/TransientQuery'
      responses:
        '200':
          description: Successful response containing flags and traits for the identity
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/IdentityResponse'
        '400':
          description: Bad request - missing identifier parameter
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: Unauthorized - invalid or missing Environment Key
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
    post:
      operationId: identifyUserAndGetFlags
      summary: Identify a user and get flags with traits
      description: >-
        Identifies a user by providing an identifier and optional traits in the
        request body. Returns the evaluated flags for that identity based on
        the provided traits and any existing traits. Traits provided in the
        request body are persisted for the identity unless marked as transient.
        This endpoint performs the entire SDK identity workflow in a single
        call.
      tags:
        - Identities
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/IdentityRequest'
      responses:
        '200':
          description: Successful response containing evaluated flags and persisted traits
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/IdentityResponse'
        '400':
          description: Bad request - missing or invalid identifier
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: Unauthorized - invalid or missing Environment Key
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /traits/:
    post:
      operationId: setTraits
      summary: Set traits for an identity
      description: >-
        Sets one or more trait values for a given identity. If the identity
        does not exist, it will be created. Traits are key-value pairs
        associated with an identity that can be used for segment evaluation
        and personalized flag delivery.
      tags:
        - Identities
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/TraitRequest'
      responses:
        '200':
          description: Successful response confirming the trait was set
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Trait'
        '400':
          description: Bad request - missing or invalid trait data
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: Unauthorized - invalid or missing Environment Key
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /traits/bulk/:
    put:
      operationId: setBulkTraits
      summary: Set multiple traits for an identity in bulk
      description: >-
        Sets multiple trait values for a given identity in a single API call.
        This is more efficient than making individual trait requests when
        updating multiple traits at once. If a trait value is set to null, the
        trait will be deleted.
      tags:
        - Identities
      requestBody:
        required: true
        content:
          application/json:
            schema:
              type: array
              items:
                $ref: '#/components/schemas/TraitRequest'
      responses:
        '200':
          description: Successful response confirming the traits were set
          content:
            application/json:
              schema:
                type: array
                items:
                  $ref: '#/components/schemas/Trait'
        '400':
          description: Bad request - missing or invalid trait data
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
        '401':
          description: Unauthorized - invalid or missing Environment Key
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
components:
  securitySchemes:
    environmentKey:
      type: apiKey
      in: header
      name: X-Environment-Key
      description: >-
        A non-secret environment key used to identify which Flagsmith
        environment to evaluate flags against. This key is safe to include
        in client-side code.
  parameters:
    FeatureNameQuery:
      name: feature
      in: query
      description: >-
        Optional feature name to filter flags. When provided, returns only the
        flag matching the specified feature name.
      required: false
      schema:
        type: string
    IdentifierQuery:
      name: identifier
      in: query
      description: >-
        The unique identifier for the user identity. This is typically a user
        ID, email, or other unique string that identifies the user in your
        application.
      required: true
      schema:
        type: string
    TransientQuery:
      name: transient
      in: query
      description: >-
        When set to true, the identity is treated as transient and will not be
        persisted. The identity will be used for flag evaluation only.
      required: false
      schema:
        type: boolean
  schemas:
    Flag:
      type: object
      description: >-
        A feature flag object containing the feature definition, its enabled
        state, and any associated value for the environment.
      properties:
        id:
          type: integer
          description: The unique identifier for this feature state
        feature:
          $ref: '#/components/schemas/Feature'
        feature_state_value:
          description: >-
            The value associated with this feature state. Can be a string,
            integer, boolean, or null depending on the feature configuration.
          oneOf:
            - type: string
            - type: integer
            - type: boolean
            - type: 'null'
        enabled:
          type: boolean
          description: Whether this feature flag is currently enabled
        environment:
          type: integer
          description: The ID of the environment this flag belongs to
        identity:
          type: integer
          nullable: true
          description: >-
            The identity ID if this is an identity-specific override, or null
            for environment defaults
        feature_segment:
          type: integer
          nullable: true
          description: >-
            The feature segment ID if this flag state is a segment override,
            or null otherwise
    Feature:
      type: object
      description: >-
        A feature definition containing metadata about the feature flag
        including its name, type, and default configuration.
      properties:
        id:
          type: integer
          description: The unique identifier for this feature
        name:
          type: string
          description: The name of the feature flag
        created_date:
          type: string
          format: date-time
          description: The date and time the feature was created
        description:
          type: string
          nullable: true
          description: A human-readable description of the feature
        initial_value:
          type: string
          nullable: true
          description: The initial value assigned to the feature when created
        default_enabled:
          type: boolean
          description: Whether the feature is enabled by default
        type:
          type: string
          enum:
            - STANDARD
            - MULTIVARIATE
          description: >-
            The type of feature flag. STANDARD for simple on/off flags,
            MULTIVARIATE for flags with multiple value variations.
    IdentityResponse:
      type: object
      description: >-
        The response object for an identity flags request, containing the
        evaluated flags and traits for the specified identity.
      properties:
        flags:
          type: array
          description: The evaluated feature flags for this identity
          items:
            $ref: '#/components/schemas/Flag'
        traits:
          type: array
          description: The traits associated with this identity
          items:
            $ref: '#/components/schemas/Trait'
    IdentityRequest:
      type: object
      description: >-
        The request body for identifying a user and optionally setting traits.
      required:
        - identifier
      properties:
        identifier:
          type: string
          description: >-
            The unique identifier for the user identity in your application.
        traits:
          type: array
          description: >-
            An optional array of traits to set for this identity. Traits are
            used for segment evaluation and personalized flag delivery.
          items:
            $ref: '#/components/schemas/TraitInput'
        transient:
          type: boolean
          description: >-
            When true, the identity is transient and will not be persisted.
    Trait:
      type: object
      description: >-
        A trait is a key-value pair associated with an identity, used for
        segment evaluation and personalization.
      properties:
        id:
          type: integer
          description: The unique identifier for this trait
        trait_key:
          type: string
          description: The key name of the trait
        trait_value:
          description: >-
            The value of the trait. Can be a string, integer, float, or boolean.
          oneOf:
            - type: string
            - type: integer
            - type: number
            - type: boolean
    TraitInput:
      type: object
      description: >-
        Input object for setting a trait value on an identity.
      required:
        - trait_key
        - trait_value
      properties:
        trait_key:
          type: string
          description: The key name of the trait to set
        trait_value:
          description: >-
            The value to set for the trait. Can be a string, integer, float,
            or boolean. Set to null to delete the trait.
          oneOf:
            - type: string
            - type: integer
            - type: number
            - type: boolean
            - type: 'null'
        transient:
          type: boolean
          description: >-
            When true, this trait is transient and will be used for evaluation
            but not persisted.
    TraitRequest:
      type: object
      description: >-
        Request body for setting a trait on an identity.
      required:
        - identity
        - trait_key
        - trait_value
      properties:
        identity:
          type: object
          description: The identity to set the trait on
          required:
            - identifier
          properties:
            identifier:
              type: string
              description: The unique identifier for the user identity
        trait_key:
          type: string
          description: The key name of the trait to set
        trait_value:
          description: >-
            The value to set for the trait. Set to null to delete the trait.
          oneOf:
            - type: string
            - type: integer
            - type: number
            - type: boolean
            - type: 'null'
    Error:
      type: object
      description: An error response from the API
      properties:
        detail:
          type: string
          description: A human-readable error message