Basecamp Identity API

openapi: 3.2.0
info:
  title: Basecamp OAuth Identity API
  description: The Basecamp OAuth 2.0 API provides the authorization code flow for obtaining access tokens on behalf of Basecamp users. Developers register their applications at launchpad.37signals.com to receive a client ID and client secret, then redirect users through the authorization flow. Access tokens expire after two weeks and can be refreshed using refresh tokens without requiring the user to re-authorize. All Basecamp API requests must include a valid Bearer token obtained through this flow.
  version: '1.0'
  contact:
    name: Basecamp Developer Support
    url: https://github.com/basecamp/bc3-api/blob/master/sections/authentication.md
  termsOfService: https://basecamp.com/terms
servers:
- url: https://launchpad.37signals.com
  description: Basecamp Authorization Server
tags:
- name: Identity
  description: Retrieve authenticated user identity
paths:
  /authorization.json:
    get:
      operationId: getIdentity
      summary: Get identity
      description: Returns the identity of the authenticated user along with the list of Basecamp accounts they have access to. This is typically the first call made after obtaining an access token to discover which account IDs to use in subsequent API requests.
      tags:
      - Identity
      security:
      - bearerAuth: []
      responses:
        '200':
          description: Authenticated user identity and accessible accounts
          content:
            application/json:
              schema:
                $ref: '#/components/schemas/Identity'
        '401':
          $ref: '#/components/responses/Unauthorized'
components:
  schemas:
    Error:
      type: object
      properties:
        error:
          type: string
          description: Human-readable error message
    Account:
      type: object
      properties:
        product:
          type: string
          description: Product name (e.g., "bc3")
        id:
          type: integer
          description: Account ID used in API base URLs
        name:
          type: string
          description: Account name
        href:
          type: string
          format: uri
          description: API base URL for this account
        app_href:
          type: string
          format: uri
          description: Web URL for this account
    IdentityUser:
      type: object
      properties:
        id:
          type: integer
          description: User ID
        first_name:
          type: string
          description: User's first name
        last_name:
          type: string
          description: User's last name
        email_address:
          type: string
          format: email
          description: User's email address
    Identity:
      type: object
      properties:
        expires_at:
          type: string
          format: date-time
          description: Timestamp when the current access token expires
        identity:
          $ref: '#/components/schemas/IdentityUser'
        accounts:
          type: array
          description: Basecamp accounts the authenticated user has access to
          items:
            $ref: '#/components/schemas/Account'
  responses:
    Unauthorized:
      description: Unauthorized — invalid or expired credentials
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: 'OAuth 2.0 Bearer token obtained via the authorization code flow. Include as "Authorization: Bearer {token}" in all API requests.'
externalDocs:
  description: Basecamp Authentication Documentation
  url: https://github.com/basecamp/bc3-api/blob/master/sections/authentication.md