Cortex generates SDKs and docs from one spec file

Cortex turns one spec file into typed SDKs, docs and an MCP server, per its GitHub repo. Fern, Stoplight and ReadMe charge monthly for exactly that combination: SDK generation, hosted docs and agent integration. Cortex does it under an MIT license, for free.

The tool reads OpenAPI, AsyncAPI, GraphQL, gRPC, OpenRPC and custom Markdown from a single project config, then generates SDKs in multiple languages. The repo has 64 stars and pushed its latest commit the morning of September 12.

The MCP server is new. It hands agents typed tools, the underlying specs and SDK guides directly.

The repo doesn't say how it handles versioning across breaking spec changes. It also doesn't say whether the generated SDKs match a paid tool's polish after years of fixes. Sixty-four stars is early traction, not proof the generation holds up at scale.

Teams already paying Fern or ReadMe may now run Cortex against their specs as a side-by-side test. If the SDKs hold up, the case for a subscription doc platform gets harder to make. Smaller teams without enterprise support needs have the least reason to pay.