Featureflip

Featureflip Server SDK API

SDK endpoints for feature flag evaluation and configuration retrieval. All endpoints require a valid SDK key passed via the Authorization header.

GitHub OpenAPI

Operations 5

GET /v1/sdk/flags Retrieves all feature flags for the authenticated environment #
GET /v1/sdk/flags/{key} Retrieves a specific feature flag by key #
POST /v1/sdk/evaluate Evaluates a feature flag for the given context #
POST /v1/sdk/events Records SDK events for analytics and debugging #
GET /v1/sdk/stream Opens a Server-Sent Events stream for real-time flag updates #

Documentation

📖
APIReference
https://featureflip.io/docs/management-api/reference/
📖
Documentation
https://featureflip.io/docs/management-api/reference/
📖
Documentation
https://featureflip.io/docs/management-api/authentication/
📖
APIReference
https://featureflip.io/docs/api/reference/
📖
Documentation
https://featureflip.io/docs/api/reference/

Specifications

⚙
OpenAPI
https://raw.githubusercontent.com/api-evangelist/featureflip/refs/heads/main/openapi/featureflip-server-sdk-api-openapi.yml

Other Resources

🔗
LLMsTxt
https://featureflip.io/llms.txt

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OpenAPI Specification

featureflip-server-sdk-api-openapi.yml Raw ↑ 
openapi: 3.2.0
info:
  title: Featureflip Evaluation Server SDK API
  description: High-performance feature flag evaluation service for SDKs
  version: v1
servers:
- url: https://eval.featureflip.io
  description: Production
security:
- Bearer: []
tags:
- name: Server SDK
  description: 'SDK endpoints for feature flag evaluation and configuration retrieval.

    All endpoints require a valid SDK key passed via the Authorization header.'
paths:
  /v1/sdk/flags:
    get:
      tags:
      - Server SDK
      summary: Retrieves all feature flags for the authenticated environment
      responses:
        '200':
          description: Returns the environment configuration.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GetFlagsResponse'
        '401':
          description: SDK key is missing or invalid.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProblemDetails'
        '503':
          description: Flag configuration is temporarily unavailable; retry after the interval in `Retry-After`.
      operationId: getV1SdkFlags
      x-operation-id-source: derived
  /v1/sdk/flags/{key}:
    get:
      tags:
      - Server SDK
      summary: Retrieves a specific feature flag by key
      parameters:
      - name: key
        in: path
        description: The flag key to retrieve.
        required: true
        schema:
          type: string
      responses:
        '200':
          description: Returns the flag configuration.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/FlagDto'
        '401':
          description: SDK key is missing or invalid.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProblemDetails'
        '404':
          description: Flag with the specified key was not found.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProblemDetails'
        '503':
          description: Flag configuration is temporarily unavailable; retry after the interval in `Retry-After`.
      operationId: getV1SdkFlagsByKey
      x-operation-id-source: derived
  /v1/sdk/evaluate:
    post:
      tags:
      - Server SDK
      summary: Evaluates a feature flag for the given context
      requestBody:
        description: The evaluation request containing flag key and context.
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/EvaluateFlagRequest'
          text/json:
            schema:
              $ref: '#/components/schemas/EvaluateFlagRequest'
          application/*+json:
            schema:
              $ref: '#/components/schemas/EvaluateFlagRequest'
      responses:
        '200':
          description: Returns the evaluation result.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/EvaluateFlagResponse'
        '401':
          description: SDK key is missing or invalid.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProblemDetails'
        '404':
          description: Flag with the specified key was not found.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProblemDetails'
        '503':
          description: Service Unavailable
      operationId: postV1SdkEvaluate
      x-operation-id-source: derived
  /v1/sdk/events:
    post:
      tags:
      - Server SDK
      summary: Records SDK events for analytics and debugging
      requestBody:
        description: Batch of events to record.
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/RecordEventsRequest'
          text/json:
            schema:
              $ref: '#/components/schemas/RecordEventsRequest'
          application/*+json:
            schema:
              $ref: '#/components/schemas/RecordEventsRequest'
      responses:
        '202':
          description: Events were accepted for processing.
        '401':
          description: SDK key is missing or invalid.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProblemDetails'
      operationId: postV1SdkEvents
      x-operation-id-source: derived
  /v1/sdk/stream:
    get:
      tags:
      - Server SDK
      summary: Opens a Server-Sent Events stream for real-time flag updates
      responses:
        '200':
          description: SSE stream opened successfully.
        '401':
          description: SDK key is missing or invalid.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ProblemDetails'
        '503':
          description: Flag configuration is temporarily unavailable; retry after the interval in `Retry-After`.
      operationId: getV1SdkStream
      x-operation-id-source: derived
components:
  schemas:
    SdkEventType:
      enum:
      - Evaluation
      - Impression
      - Identify
      - Custom
      type: string
    ConditionLogic:
      enum:
      - And
      - Or
      type: string
    EvaluateFlagResponse:
      required:
      - key
      - reason
      - value
      - variation
      type: object
      properties:
        key:
          type:
          - string
          - 'null'
        variation:
          type:
          - string
          - 'null'
        value: {}
        reason:
          type:
          - string
          - 'null'
        prerequisiteKey:
          type:
          - string
          - 'null'
      additionalProperties: false
    PrerequisiteDto:
      required:
      - expectedVariationKey
      - prerequisiteFlagKey
      type: object
      properties:
        prerequisiteFlagKey:
          type:
          - string
          - 'null'
        expectedVariationKey:
          type:
          - string
          - 'null'
      additionalProperties: false
    ProblemDetails:
      type: object
      properties:
        type:
          type:
          - string
          - 'null'
        title:
          type:
          - string
          - 'null'
        status:
          type:
          - integer
          - 'null'
          format: int32
        detail:
          type:
          - string
          - 'null'
        instance:
          type:
          - string
          - 'null'
      additionalProperties: {}
    ServeType:
      enum:
      - Fixed
      - Rollout
      type: string
    RuleDto:
      required:
      - conditionGroups
      - id
      - priority
      - serve
      type: object
      properties:
        id:
          type:
          - string
          - 'null'
        priority:
          type: integer
          format: int32
        conditionGroups:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/ConditionGroupDto'
        serve:
          $ref: '#/components/schemas/ServeConfigDto'
        segmentKey:
          type:
          - string
          - 'null'
      additionalProperties: false
    EvaluationContextDto:
      type: object
      properties:
        userId:
          type:
          - string
          - 'null'
        attributes:
          type:
          - object
          - 'null'
          additionalProperties: {}
      additionalProperties: false
    SdkEventDto:
      required:
      - flagKey
      - type
      type: object
      properties:
        type:
          $ref: '#/components/schemas/SdkEventType'
        flagKey:
          type:
          - string
          - 'null'
        userId:
          type:
          - string
          - 'null'
        variation:
          type:
          - string
          - 'null'
        timestamp:
          type: string
          format: date-time
        metadata:
          type:
          - object
          - 'null'
          additionalProperties: {}
        prerequisiteKey:
          type:
          - string
          - 'null'
      additionalProperties: false
    EvaluateFlagRequest:
      required:
      - context
      - flagKey
      type: object
      properties:
        flagKey:
          type:
          - string
          - 'null'
        context:
          $ref: '#/components/schemas/EvaluationContextDto'
      additionalProperties: false
    ConditionDto:
      required:
      - attribute
      - operator
      - values
      type: object
      properties:
        attribute:
          type:
          - string
          - 'null'
        operator:
          $ref: '#/components/schemas/ConditionOperator'
        values:
          type:
          - array
          - 'null'
          items:
            type: string
        negate:
          type: boolean
      additionalProperties: false
    ConditionOperator:
      enum:
      - Equals
      - NotEquals
      - Contains
      - NotContains
      - StartsWith
      - EndsWith
      - In
      - NotIn
      - MatchesRegex
      - GreaterThan
      - LessThan
      - GreaterThanOrEqual
      - LessThanOrEqual
      - Before
      - After
      - SemverEquals
      - SemverGreaterThan
      - SemverGreaterThanOrEqual
      - SemverLessThan
      - SemverLessThanOrEqual
      type: string
    SegmentDto:
      required:
      - conditionLogic
      - conditions
      - key
      - version
      type: object
      properties:
        key:
          type:
          - string
          - 'null'
        version:
          type: integer
          format: int32
        conditions:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/ConditionDto'
        conditionLogic:
          $ref: '#/components/schemas/ConditionLogic'
      additionalProperties: false
    FlagDto:
      required:
      - enabled
      - fallthrough
      - key
      - offVariation
      - prerequisites
      - rules
      - type
      - variations
      - version
      type: object
      properties:
        key:
          type:
          - string
          - 'null'
        version:
          type: integer
          format: int32
        type:
          $ref: '#/components/schemas/FlagType'
        enabled:
          type: boolean
        variations:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/VariationDto'
        rules:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/RuleDto'
        fallthrough:
          $ref: '#/components/schemas/ServeConfigDto'
        offVariation:
          type:
          - string
          - 'null'
        prerequisites:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/PrerequisiteDto'
      additionalProperties: false
    RecordEventsRequest:
      required:
      - events
      type: object
      properties:
        events:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/SdkEventDto'
      additionalProperties: false
    GetFlagsResponse:
      required:
      - environment
      - flags
      - segments
      - version
      type: object
      properties:
        environment:
          type:
          - string
          - 'null'
        version:
          type: integer
          format: int32
        flags:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/FlagDto'
        segments:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/SegmentDto'
      additionalProperties: false
    WeightedVariationDto:
      required:
      - key
      - weight
      type: object
      properties:
        key:
          type:
          - string
          - 'null'
        weight:
          type: integer
          format: int32
      additionalProperties: false
    VariationDto:
      required:
      - key
      - value
      type: object
      properties:
        key:
          type:
          - string
          - 'null'
        value: {}
      additionalProperties: false
    FlagType:
      enum:
      - Boolean
      - String
      - Number
      - Json
      type: string
    ConditionGroupDto:
      required:
      - conditions
      - operator
      type: object
      properties:
        operator:
          $ref: '#/components/schemas/ConditionLogic'
        conditions:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/ConditionDto'
      additionalProperties: false
    ServeConfigDto:
      required:
      - type
      type: object
      properties:
        type:
          $ref: '#/components/schemas/ServeType'
        variation:
          type:
          - string
          - 'null'
        bucketBy:
          type:
          - string
          - 'null'
        salt:
          type:
          - string
          - 'null'
        variations:
          type:
          - array
          - 'null'
          items:
            $ref: '#/components/schemas/WeightedVariationDto'
      additionalProperties: false
  securitySchemes:
    Bearer:
      type: apiKey
      description: SDK Key authorization. Enter your SDK key.
      name: Authorization
      in: header