Choose and implement 2-legged vs 3-legged OAuth for an Autodesk Platform Services (APS) app
domain: aps.autodesk.com · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Use 2-legged (Client Credentials): POST /authentication/v2/token with grant_type=client_credentials and Basic auth of client_id:client_secret for server-to-server apps with no specific user context
Use 3-legged (Authorization Code, optionally with PKCE): GET /authentication/v2/authorize with client_id, response_type=code, redirect_uri, scope, then POST /authentication/v2/token with grant_type=authorization_code
Request only the minimum scopes needed (data:read, data:write, account:read, etc.); the scope string is capped at 2000 characters / 50 scopes
Refresh 3-legged tokens with grant_type=refresh_token before the 60-minute access token expires; refresh tokens last 15 days
For ACC/BIM 360 endpoints that support impersonation with a 2-legged token, add a User-Id header identifying the acting user (the app must be granted access to that user by an admin)
Known gotchas
Authorization codes expire in 5 minutes and are single-use - an invalid_grant error usually means it already expired or was reused
Construction-related APIs (Issues, Cost, Assets) additionally require a regional header (Region or x-ads-region: US/EMEA) matching the project's data residency, independent of the auth flow
2-legged tokens alone cannot access user-specific ACC/BIM 360 data without either 3-legged auth or the User-Id impersonation header plus admin-granted access
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