Open Source ReadMe Alternatives

Scalar takes an OpenAPI or Swagger document and renders it as an interactive API reference that does not look like it was designed in 2011. Next to it sits an API client for calling the endpoints, so reading a specification and trying it become the same activity.

Publishing a reference is a single HTML file: load the package from a script tag, point it at your document, and add a proxy address for the CORS problem that always turns up. Code examples are generated for many languages and frameworks from the same document.

The surrounding pieces are worth knowing about.

• API client: offline-first and open source, with environment variables and dynamic parameters, in the browser or downloaded for Windows, macOS and Linux.
• Watch mode: the client keeps itself in sync with your server framework as the specification changes.
• Framework integrations: ASP.NET Core, Django, Express, FastAPI, Fastify, Flask, Go, Spring Boot, SvelteKit, Vue and dozens more.
• Built-in adoption: Effect, ElysiaJS, Litestar, Nitro, oRPC and Platformatic ship Scalar as their default OpenAPI interface.
• Supporting tools: a registry for managing documents, an SDK generator, a CLI, a mock server and an online editor.

Everything here can be self-hosted straight from the repository. A managed service is offered alongside it, with a free tier that publishes references on a project subdomain with SSL, GitHub sync, free-form documentation, team collaboration and support for your own domain.

Fumadocs is a framework for building documentation websites in React.js frameworks and Astro. Every documentation site needs the same scaffolding, a content pipeline, navigation, search and a readable theme, and Fumadocs supplies those so a team stops rebuilding them for each new project.

The design is compositional rather than a single template. A headless core handles content and navigation, a UI package supplies the themed pieces, and an MDX integration handles the writing layer, so a site can take the full theme or drop to headless mode and build its own. Officially supported targets are Next.js, Astro with React, and Vite setups including Tanstack Start, Waku and React Router.

The packages split along clear lines.

• fumadocs-core: a headless library for docs management, content handling and navigation.
• fumadocs-ui: the themed components, customized through Tailwind CSS.
• fumadocs-mdx: the Markdown and MDX layer, with Shiki highlighting, codeblock grouping and callouts.
• fumadocs-openapi: renders OpenAPI documentation from a schema.
• fumadocs-obsidian: reads Obsidian style Markdown syntax.

Content does not have to live in files. Fumadocs reads MDX, Content Collections and external content managers such as BaseHub, Sanity and Payload CMS, while search plugs into Orama or Algolia. Server Components, Twoslash TypeScript documentation and Storybook integration are supported. All packages are ESM only, a CLI scaffolds a project and customizes the theme interactively, and the project is community funded rather than backed by a company.

xyd is a documentation framework aimed squarely at developer docs. Install it globally, run one command for a dev server with hot reload and another to build static files, and a docs site exists before any configuration work begins.

It comes out of LiveSession, who needed a docs tool for their analytics platform and released the whole thing rather than a trimmed version. Node 22.12 or later is required. Several packages behind it stand on their own too, including a docs writing engine and a set of API docs tooling, and the components follow a design system published as a Storybook.

What arrives with the framework goes well past page rendering.

• Themes: six built-in themes are published separately and swap in without a rewrite.
• API reference: reference pages generate from OpenAPI and GraphQL specifications.
• SDK generation: client SDKs are produced from those same specifications.
• Search: full text search with typo tolerance and relevance scoring is built in.
• Plugins: search, analytics, chat and more arrive through a plugin ecosystem.
• Experiments: A/B testing integrates with LaunchDarkly and GrowthBook.
• Live chat: Intercom, LiveChat and Chatwoot embed into the docs themselves.

Deploy templates exist for Netlify, Vercel and CodeSandbox, a starter and ready to run examples are published separately, and a migration tool moves docs off several other frameworks. xyd suits a team whose documentation has to carry API reference, analytics and experiments, not prose alone.