Backend APIs: HTTP Service Design and Implementation

Design and review HTTP APIs that stay coherent as they grow. Focus on contracts, auth boundaries, error models, and framework structure for Python and Node.js services.

Target versions (July 2026):

• FastAPI 0.139.2
• Express 5.2.1 (published 2025-12-01)
• NestJS 11.1.28
• OpenAPI Specification 3.2.0 (published 2025-09-19)
• HTTP Semantics: RFC 9110 (June 2022)
• Problem Details for HTTP APIs: RFC 9457 (July 2023)
• OAuth 2.0 Security Best Current Practice: RFC 9700 (January 2025)