What is api-blueprint?

API Blueprint is a way to document and describe web APIs using simple, human-readable text. Think of it as a template language built on top of Markdown, the same easy formatting you'd use to write a README on GitHub. Instead of writing long prose or complex XML, you write clean, structured text that describes what your API does, what endpoints it has, and what responses it returns. The basic idea is straightforward: you write a few lines of plain text describing an endpoint (like "GET /message"), what it returns (like "200 OK with plain text"), and example data. That's it. A developer reading your file immediately understands the API without needing to hunt through separate documentation or decipher cryptic specifications. What makes this useful is that the format works two ways. Humans can read and edit it easily in any text editor. But machines can also parse it. The README mentions a tool called Drafter that converts your human-friendly API Blueprint into a structured data format (JSON) that other software can consume. That means you write the API description once, and then many different tools can automatically generate interactive documentation, mock servers that pretend to be your API for testing, SDK code generators, or API testing tools. You get all of that from a single source file. Who uses this? Developers designing new APIs before building them, teams collaborating on API design in GitHub by reviewing and discussing the spec like code, and anyone who wants their API documented without the pain of maintaining separate documentation files. It's especially useful for startups and teams that want to iterate quickly, you can share a rough API design with stakeholders or colleagues, get feedback, and update it all in one place. Since it's open source and vendor-neutral, you don't lock yourself into any single company's tools or proprietary formats.