Guides
The API engineering guides
Eight focused guides covering OpenAPI, API testing, mocking, debugging, code generation, MCP servers, AI coding agents, and the Postman alternatives worth using in 2026. Start with a hub and follow the links.
OpenAPI
The OpenAPI Guide
What the spec is, what changed in 3.2, how to structure a real document, reuse components, and keep it as the single source of truth.
Open the guide →Testing
The API Testing Guide
Unit, contract, scenario, and property-based testing; breaking-change detection; and how to test SSE, WebSocket, and async APIs.
Open the guide →Mocking
The API Mocking Guide
Mock servers and service virtualization, MSW vs Prism, and how to keep frontend work moving when the backend is late.
Open the guide →Debugging
The API Debugging Guide
The failures that return 200 but still break, CORS and content-type traps, and why a curl command is never a handoff.
Open the guide →Code generation
The Code Generation Guide
Generate TypeScript clients and servers from the spec, or scan Express, FastAPI, and Django code to recover a spec without hallucinating.
Open the guide →MCP
The MCP Server Guide
Turn an OpenAPI spec into MCP tools, choose stdio vs HTTP, handle auth and security, and version tools without breaking agents.
Open the guide →AI coding
The AI Coding Agent Guide
Give agents the right context, keep them on the contract, and verify "done" with runnable commands instead of a green summary.
Open the guide →Alternatives
Postman Alternatives in 2026
Local-first, OpenAPI-first options compared honestly, including Bruno, Hoppscotch, Insomnia, and Stoplight, with the real tradeoffs.
Open the guide →