LaunchDarkly

launchdarkly Client-Side Evaluation API

Flag evaluation endpoints for client-side and mobile SDKs using environment IDs or mobile keys for authentication.

GitHub OpenAPI
Business capability
Feature Flag Management BC-4210.50

Operations 1

Each operation below carries the questions people ask an LLM about it and the instructions they give an agent to run it. Generated by API Evangelist overlay

GET /sdk/evalx/{envId}/contexts/{contextBase64} Evaluate client-side flags for a context · Evaluate all flags for a client-side context (GET) #
Ask an LLM
“How do I get all client-side flag values for a user from the browser?”
“Can I evaluate flags using only the client-side environment ID?”
Tell an agent
Evaluate all client-side flags in environment {envId} for context {contextBase64}.
Get the client-side flag values for encoded context {contextBase64} in env {envId}.

Documentation

📖
Documentation
https://launchdarkly.com/docs/api
📖
Documentation
https://launchdarkly.com/docs/sdk/relay-proxy

Specifications

⚙
OpenAPI
https://raw.githubusercontent.com/api-evangelist/launchdarkly/refs/heads/main/openapi/launchdarkly-client-side-evaluation-api-openapi.yml

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OpenAPI Specification

launchdarkly-client-side-evaluation-api-openapi.yml Raw ↑ 
openapi: 3.2.0
info:
  title: LaunchDarkly Relay Proxy Client-Side Evaluation API
  description: The LaunchDarkly Relay Proxy is a small Go application that connects to the LaunchDarkly streaming API and proxies that connection to SDK clients within an organization's network. It exposes endpoints for status monitoring, flag evaluation, and SDK streaming that mirror the LaunchDarkly service endpoints. Instead of each server making outbound connections to LaunchDarkly's streaming service, multiple servers connect to the local Relay Proxy which maintains a single upstream connection.
  version: '8.0'
  contact:
    name: LaunchDarkly Support
    url: https://support.launchdarkly.com
  license:
    name: Apache 2.0
    url: https://www.apache.org/licenses/LICENSE-2.0
servers:
- url: http://localhost:8030
  description: Default Relay Proxy instance
tags:
- name: Client-Side Evaluation
  description: Flag evaluation endpoints for client-side and mobile SDKs using environment IDs or mobile keys for authentication.
paths:
  /sdk/evalx/{envId}/contexts/{contextBase64}:
    get:
      operationId: evaluateAllFlagsClientSide
      summary: Evaluate all flags for a client-side context (GET)
      description: Evaluates all client-side enabled feature flags for the given context. Uses the environment ID in the URL path for authentication.
      tags:
      - Client-Side Evaluation
      parameters:
      - $ref: '#/components/parameters/EnvironmentId'
      - $ref: '#/components/parameters/ContextBase64'
      responses:
        '200':
          description: Successful response with all client-side flag evaluations.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/FlagEvaluations'
        '401':
          description: Unauthorized. Invalid environment ID.
        '503':
          description: Service unavailable. Flag data not yet available.
components:
  parameters:
    EnvironmentId:
      name: envId
      in: path
      required: true
      description: The client-side environment ID.
      schema:
        type: string
    ContextBase64:
      name: contextBase64
      in: path
      required: true
      description: A base64-encoded JSON representation of the evaluation context.
      schema:
        type: string
  schemas:
    FlagEvaluations:
      type: object
      description: A map of flag keys to their evaluated results for a context.
      additionalProperties:
        $ref: '#/components/schemas/FlagEvaluation'
    FlagEvaluation:
      type: object
      description: The evaluated result of a single feature flag.
      properties:
        value:
          description: The evaluated value of the flag for the given context.
        variation:
          type: integer
          description: The index of the variation that was served.
        version:
          type: integer
          description: The version number of the flag.
        trackEvents:
          type: boolean
          description: Whether analytics events should be tracked for this flag.
        trackReason:
          type: boolean
          description: Whether the evaluation reason should be included in events.
        reason:
          type: object
          description: The reason for the evaluation result.
          properties:
            kind:
              type: string
              description: The kind of evaluation reason.
              enum:
              - 'OFF'
              - FALLTHROUGH
              - TARGET_MATCH
              - RULE_MATCH
              - PREREQUISITE_FAILED
              - ERROR
  securitySchemes:
    sdkKeyAuth:
      type: apiKey
      in: header
      name: Authorization
      description: Server-side SDK key for authenticating with the Relay Proxy.
    mobileKeyAuth:
      type: apiKey
      in: header
      name: Authorization
      description: Mobile SDK key for authenticating with the Relay Proxy.
externalDocs:
  description: Relay Proxy Documentation
  url: https://launchdarkly.com/docs/sdk/relay-proxy