Open-source Heretto alternatives

Cortex turns API specifications and Markdown files into developer-facing outputs from a single project configuration. It reads sources such as OpenAPI, AsyncAPI, GraphQL, Protocol Buffers, OpenRPC, and plain Markdown, and produces interactive documentation for people, typed SDKs for applications, and an MCP server so AI agents can work with the same project context. It is released under the MIT license.

Generated SDKs cover many languages, including TypeScript, Python, Go, Java, Kotlin, Ruby, PHP, Rust, and C++, and can combine several specification files into one client. The tool supports HTTP, WebSocket, GraphQL, gRPC, and JSON-RPC clients, and builds static HTML documentation with interactive API reference pages. The MCP server includes typed tools, embedded specifications, and SDK guides.

You can try a local demo in about a minute, keep documentation in Git, and publish a free site for a public GitHub repository through the project's hosting flow. It suits API providers and developer-experience teams who want one source of truth for docs, client libraries, and agent access.

Gramax is a free, open-source application for creating, editing and publishing documentation as code. It stores all data locally in Markdown, so it works offline and files can be edited in any text editor, and it integrates with Git for version control and collaboration. It targets product documentation portals, internal knowledge bases, project documentation and personal notes.

A visual editor makes Markdown editing easier for technical and non-technical users. The app runs on Windows, macOS and Linux as a desktop app and as a web version. Editing features include tabs, tables, video embeds, code blocks, diagrams from Mermaid, Excalidraw and Diagrams.net, and Swagger API descriptions. Git repositories on GitHub, GitLab, Bitbucket, Gitea and others can be connected, catalogs can be published to a customizable documentation portal, documentation can be written in 17 languages, and content can be imported from Confluence and Notion.

Gramax is positioned as an alternative to GitBook, Mintlify and typical static site generators. It is written in TypeScript and Rust with Tauri, and licensed under GPL-3.0.