openapi: 3.0.1
info:
  title: Langtrace AI API
  description: >-
    REST API for Langtrace, an open-source, OpenTelemetry-based observability
    platform for LLM applications by Scale3 Labs. Covers OTLP/HTTP trace
    ingestion, project and API key management, the prompt registry, and
    paginated trace retrieval. The same endpoints are available on Langtrace
    Cloud (app.langtrace.ai) and on self-hosted deployments. All requests are
    authenticated with an x-api-key header.
  termsOfService: https://www.langtrace.ai/terms
  contact:
    name: Langtrace AI Support
    url: https://docs.langtrace.ai
  license:
    name: AGPL-3.0
    url: https://github.com/Scale3-Labs/langtrace/blob/main/LICENSE
  version: '1.0'
servers:
  - url: https://app.langtrace.ai/api
    description: Langtrace Cloud
  - url: http://localhost:3000/api
    description: Self-hosted Langtrace deployment
security:
  - ApiKeyAuth: []
tags:
  - name: Traces
    description: OpenTelemetry trace ingestion and retrieval.
  - name: Projects
    description: Project and API key management.
  - name: Prompt Registry
    description: Versioned prompt storage and retrieval.
paths:
  /trace:
    post:
      operationId: sendTrace
      tags:
        - Traces
      summary: Send OpenTelemetry-compatible traces to Langtrace.
      description: >-
        Ingests JSON-encoded OTLP/HTTP spans. Use an OTEL exporter configured
        for the otlphttp protocol with JSON encoding and no compression, and set
        the x-api-key header to a project-level API key. Available on Langtrace
        Cloud and self-hosted instances.
      requestBody:
        required: true
        description: An OTLP/HTTP ExportTraceServiceRequest payload, JSON-encoded.
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/OTLPTraceExportRequest'
      responses:
        '200':
          description: Traces accepted for ingestion.
        '401':
          description: Invalid or missing API key.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /project:
    post:
      operationId: createProject
      tags:
        - Projects
      summary: Create a new project.
      description: Creates a new project under the specified team.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/CreateProjectRequest'
      responses:
        '200':
          description: Project created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Project'
        '401':
          description: Invalid api key unauthorized.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /api-key:
    post:
      operationId: createProjectApiKey
      tags:
        - Projects
      summary: Create an API key for an existing project.
      description: Mints a new project-level API key for the given project.
      parameters:
        - name: project_id
          in: query
          required: true
          description: ID of the project to create an API key for.
          schema:
            type: string
      responses:
        '200':
          description: API key created.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/ApiKeyResponse'
        '401':
          description: Invalid api key unauthorized.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /promptset:
    get:
      operationId: getPromptFromRegistry
      tags:
        - Prompt Registry
      summary: Get a prompt from the registry.
      description: >-
        Fetches a prompt set from the prompt registry. If no version is
        provided the live prompt is returned; if there are no live prompts an
        error is thrown. Dynamic variables may be supplied using
        variables.<variable_name> query parameters.
      parameters:
        - name: promptset_id
          in: query
          required: true
          description: ID of the prompt registry, found in the Langtrace UI.
          schema:
            type: string
        - name: version
          in: query
          required: false
          description: Prompt version to fetch. Defaults to the live prompt.
          schema:
            type: integer
      responses:
        '200':
          description: Prompt set returned.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/PromptSet'
        '401':
          description: Invalid api key unauthorized.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
  /traces:
    post:
      operationId: downloadTraces
      tags:
        - Traces
      summary: Download traces for a project.
      description: >-
        Retrieves stored traces for a project, paginated. Returns up to 100
        traces per page along with pagination metadata.
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/GetTracesRequest'
      responses:
        '200':
          description: Traces returned.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/GetTracesResponse'
        '401':
          description: Invalid api key unauthorized.
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Error'
components:
  securitySchemes:
    ApiKeyAuth:
      type: apiKey
      in: header
      name: x-api-key
      description: Project-level (or team-level for project creation) API key.
  schemas:
    OTLPTraceExportRequest:
      type: object
      description: >-
        OTLP/HTTP ExportTraceServiceRequest. JSON-encoded resource spans as
        produced by an OpenTelemetry exporter. See the OpenTelemetry protocol
        specification for the full structure.
      properties:
        resourceSpans:
          type: array
          items:
            type: object
    CreateProjectRequest:
      type: object
      required:
        - teamId
      properties:
        teamId:
          type: string
          description: ID of your team, found in the Langtrace UI.
        name:
          type: string
          description: Name of the project.
        description:
          type: string
          description: Description of the project being created.
        createDefaultTests:
          type: boolean
          description: Whether default tests should be created.
    Project:
      type: object
      properties:
        id:
          type: string
        name:
          type: string
        description:
          type: string
        teamId:
          type: string
        createdAt:
          type: string
          format: date-time
        updatedAt:
          type: string
          format: date-time
    ApiKeyResponse:
      type: object
      properties:
        apiKey:
          type: string
          description: The newly created project API key.
    PromptSet:
      type: object
      properties:
        id:
          type: string
        name:
          type: string
        description:
          type: string
        projectId:
          type: string
        prompts:
          type: array
          items:
            $ref: '#/components/schemas/Prompt'
        createdAt:
          type: string
          format: date-time
        updatedAt:
          type: string
          format: date-time
    Prompt:
      type: object
      properties:
        id:
          type: string
        value:
          type: string
          description: The prompt string.
        variables:
          type: array
          items:
            type: string
        model:
          type: string
        modelSettings:
          type: object
        version:
          type: integer
        live:
          type: boolean
        tags:
          type: array
          items:
            type: string
        spanId:
          type: string
        note:
          type: string
        createdAt:
          type: string
          format: date-time
        updatedAt:
          type: string
          format: date-time
    GetTracesRequest:
      type: object
      required:
        - projectId
        - page
        - pageSize
      properties:
        projectId:
          type: string
          description: ID of your project, found on the Langtrace traces tab.
        page:
          type: integer
          description: Page number to retrieve. Starts from 1.
        pageSize:
          type: integer
          maximum: 100
          description: Number of traces to retrieve per page. Maximum value is 100.
    GetTracesResponse:
      type: object
      properties:
        traces:
          type: object
          properties:
            result:
              type: array
              items:
                type: object
              description: List of retrieved traces.
            metadata:
              type: object
              properties:
                page:
                  type: integer
                page_size:
                  type: integer
                total_pages:
                  type: integer
    Error:
      type: object
      properties:
        message:
          type: string
          description: Human-readable error message.