Free API Documentation Generator

How to write API documentation

What makes good API documentation?

Good API docs start with a clear base URL and auth scheme, then document each endpoint with the HTTP method, path, parameters, a request example, and the expected response. They cover error codes, rate limits, and pagination. Above all, they show copy-pasteable examples a developer can try in under a minute.

Should I use Markdown or OpenAPI?

Use both. Maintain an OpenAPI spec as your single source of truth — it powers interactive docs (Swagger UI, Redoc), client generation, and automated testing. Generate a Markdown reference for GitHub READMEs and docs sites. This tool outputs both so you don't have to write them separately.

What is the OpenAPI Specification?

OpenAPI (formerly Swagger) is the industry-standard format for describing REST APIs. It defines endpoints, parameters, request/response schemas, and auth in YAML or JSON. An OpenAPI file renders into interactive documentation, drives code generation, and integrates with virtually every API tooling ecosystem.

How do I document path parameters?

Wrap path parameters in braces — for example /tasks/{id}. This tool detects {param} patterns and generates the matching parameter blocks in both the Markdown reference and the OpenAPI paths object automatically.

Is this tool free?

Yes — no signup, no account, no cost. Everything runs client-side in your browser; your API details never leave your machine. The generated docs are yours to use in any project.