Basecamp Identity API

openapi: 3.1.0
info:
  title: Basecamp Authorization Identity API
  description: The Basecamp API is a REST API that provides programmatic access to Basecamp's project management and team communication platform. It enables developers to manage projects, to-do lists, messages, documents, schedules, campfires, uploads, card tables, templates, and team members across Basecamp accounts. The API uses OAuth 2.0 for authentication and returns JSON responses, with all requests scoped to an account ID in the base URL path. Resources include projects, people, to-dos, message boards, documents, card tables, campfires, questionnaires, and webhooks, covering the full breadth of Basecamp's collaboration toolset.
  version: '1.0'
  contact:
    name: Basecamp Developer Support
    url: https://github.com/basecamp/bc3-api
  termsOfService: https://basecamp.com/terms
servers:
- url: https://3.basecampapi.com/{accountId}
  description: Production Server
  variables:
    accountId:
      description: Your Basecamp account ID
      default: '999999999'
security:
- bearerAuth: []
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:
  responses:
    Unauthorized:
      description: Unauthorized — invalid or expired credentials
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
  schemas:
    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'
    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
  securitySchemes:
    bearerAuth:
      type: http
      scheme: bearer
      description: 'OAuth 2.0 Bearer token obtained via the Basecamp authorization code flow at launchpad.37signals.com. Include as "Authorization: Bearer {token}" in all requests.'
externalDocs:
  description: Basecamp API Documentation
  url: https://github.com/basecamp/bc3-api