Documentation

Docusaurus64.8k★

Docusaurus builds documentation websites from Markdown files with versioning, search, i18n, and a plugin system, all using React under the hood. It's what Meta uses for React docs, and hundreds of major open source projects use it too. MIT license, TypeScript. The feature list is deep: versioned docs (keep v1 docs live while writing v2), i18n (built-in multi-language support), search (Algolia DocSearch integration), MDX support (React components inside Markdown), blog section, dark mode, and a plugin system. The sidebar is auto-generated from your file structure or manually configured. Fully free. No paid tier, no premium features. The entire platform including all plugins is open source. Deployment is free on Vercel, Netlify, GitHub Pages, or any static host. Solo to large teams: free. Docusaurus scales from a personal project wiki to massive multi-version documentation sites. The ops burden is essentially zero; it generates static HTML. The catch: it's React. Your docs site is a React app, which means slower builds than Hugo and a heavier node_modules than you'd expect for a static site. Customization beyond themes requires React knowledge. And if you don't need versioning, search, or i18n, simpler tools like VitePress or MkDocs get you there with less overhead.

Memos59.4k★

A self-hosted note-taking app that works like a private Twitter for your thoughts. If you want somewhere to quickly dump ideas, code snippets, links, and fleeting notes without the overhead of organizing them into folders or notebooks, Memos nails that workflow. Open it, type, hit enter. Done. It supports markdown, tags, image uploads, and has a timeline-based interface that feels more like a social feed than a traditional notes app. There's a built-in API, so you can pipe notes in from scripts, shortcuts, or other tools. The whole thing runs as a single Go binary with SQLite by default. docker-compose up and you're live in 30 seconds. The self-hosted version is completely free under MIT. A managed cloud version exists starting at $4.99/mo for basic use and $9.99/mo for premium features, but honestly the self-hosted version has everything. The catch: it's not a replacement for structured note-taking. If you need hierarchy, backlinks, or knowledge graph features, this isn't it. That's Obsidian or Logseq territory. Memos is for capture, not organization. The search works but isn't great for finding things months later across thousands of notes. Also, but recent development velocity has slowed to near zero. Keep an eye on whether maintenance continues.

pdf.js53.3k★

Pdf.js is the library that Firefox itself uses to render PDFs. It parses and renders PDF documents entirely in JavaScript, no plugins or native code required. Fully free under Apache 2.0. Mozilla maintains it actively. You get a complete PDF viewer with zoom, search, text selection, page navigation, and form filling. Drop it into any web app and you have a functional PDF reader. It powers Firefox's built-in PDF viewer, so it handles edge cases most alternatives can't. The catch: performance on large PDFs (100+ pages, heavy graphics) can be slow compared to native renderers. Rendering fidelity isn't perfect. Some complex PDFs with unusual fonts or annotations won't look identical to Acrobat. And if you need PDF generation (creating PDFs, not displaying them), this isn't it. Look at react-pdf or jsPDF for that. pdf.js is display-only, and it's the best at that specific job.

outline38.4k★

Outline is a team wiki built on React and Node.js that actually feels like a modern writing tool. Real-time collaboration, slash commands, markdown support, nested collections, and deep integrations with Slack, Figma, and 20+ other services. The editor is fast and clean, closer to Notion than Confluence. Search works well. Permissions are granular enough for real teams. API and webhooks let you build on top of it. Self-hosting gives you full control over your data, which matters when your wiki holds internal strategy docs and onboarding playbooks. The alternatives here are Notion (polished but closed), Confluence (enterprise bloat), and BookStack (simpler, fully open). Outline sits in the middle: more capable than BookStack, less locked-in than Notion. The BSL license means you cannot offer it as a hosted service to others. The catch: self-hosting requires Postgres, Redis, and S3-compatible storage, not a one-click setup. And the cloud pricing starts at $10/month but jumps to $79/month once you pass 10 users.

docsify31.2k★

Docsify serves your .md files directly in the browser. Drop an index.html file in your docs folder, push to GitHub Pages, done. Your Markdown becomes a website in minutes. Everything is free under MIT. No paid tier, no cloud service, no premium themes. Well-established with a solid plugin ecosystem. It's been around since 2016 and the community keeps it maintained. There's nothing to build or host in the traditional sense. Docsify loads a single JavaScript file that fetches your Markdown files at runtime and renders them in the browser. Host it on GitHub Pages ($0), Netlify ($0), or any static file server. The "deployment" is copying files. Solo developers: this is the fastest path from Markdown to docs website. If you already have docs in a GitHub repo, you can have a site live in 5 minutes. Small teams: great for internal docs, project wikis, runbooks. Growing teams: it works, but no build step means no type checking, no broken link detection at build time. The catch: because there's no build step, Docsify has worse SEO than static site generators. Search engines see a blank page until JavaScript loads and fetches the content. If public discoverability matters, use VitePress or Docusaurus instead. For internal docs where SEO doesn't matter, Docsify is perfect.

Swagger UI28.8k★

Swagger UI turns your OpenAPI spec into a live, interactive documentation page where anyone can try your API without writing code. Paste a spec file, get a browsable, testable doc site. This is the standard. Apache 2.0, used by basically every team that documents APIs. You drop it into your project, point it at your OpenAPI JSON or YAML, and your docs are live. It renders every endpoint, shows request/response schemas, and lets users hit your API right from the browser. The free version does everything most teams need. SmartBear (the company behind Swagger) sells SwaggerHub for hosted collaboration, versioning, and team management starting around $75/mo per user, but that's the platform, not the UI component. The open source UI itself has zero paywalls. The catch: it only works with OpenAPI specs. If your API isn't documented in that format, you need to write the spec first (or use a code-first tool that generates it). And the default styling looks like 2018. Functional, not pretty. Redoc looks better out of the box if aesthetics matter to you.

Redoc25.7k★

Redoc turns your OpenAPI spec into readable API documentation in one command. Drop in your spec file, get a fully rendered docs page with a three-panel layout: navigation, content, and code samples. The output is clean. Seriously clean. Better-looking than Swagger UI out of the box. It renders as a single HTML file, no server needed. Host it on GitHub Pages, Netlify, S3, or embed it in your existing site. One of the most popular API documentation generators. Used by companies from startups to enterprises. Redoc itself is free and MIT licensed. The commercial product is Redocly (the platform), which adds API linting, versioning, developer portals, and team collaboration, starting at $69/mo per project. The catch: Redoc only reads OpenAPI specs. If your API isn't documented in OpenAPI format, Redoc can't help you. It's also read-only, no "Try it" button for sending test requests like Swagger UI has. If interactive testing matters, Swagger UI or Stoplight Elements are better fits. But for pure documentation quality, Redoc wins.

MDX19.5k★

MQTT Explorer visualizes MQTT broker data in a structured tree view with real-time updates, history charts, and topic filtering. It's Markdown with JSX superpowers. Write normal Markdown. When you need something dynamic, import a React component and use it inline. That's the whole pitch. MIT licensed, used by Docusaurus, Next.js docs, Gatsby, and half the documentation sites on the internet. It's the standard for component-enhanced content. Fully free. No paid tier, no hosted service. It's a compiler that transforms your .mdx files into JavaScript. Works with every major framework: React, Vue (via plugins), Svelte, and more. The catch: MDX adds build complexity. Your content now depends on a JavaScript build pipeline. You can't just render Markdown server-side anymore. Debugging MDX compilation errors is painful, especially when you mix complex JSX with Markdown. And if your content team isn't comfortable with JSX syntax, they'll hate it. For pure Markdown with no interactivity, stick with regular .md files.

BookStack18.7k★

BookStack organizes documentation into a hierarchy that actually makes sense: shelves hold books, books hold chapters, chapters hold pages. It is a wiki built for people who think in structure, not chaos. The WYSIWYG editor works out of the box, no markdown gatekeeping required. Role-based permissions let you lock down who sees what, which matters once your team grows past five people. Multi-factor auth, audit logging, LDAP and SAML support ship built in. Diagrams.net integration, API access, and full-text search round it out. If you have tried Notion or Confluence and wanted something you actually own, this is the answer. GitBook gives you hosted convenience but locks your docs behind their platform. Outline looks slicker but needs more infrastructure to run. Wiki.js is the other serious self-hosted option but feels more generic. The catch: it is PHP and Laravel, so you need a traditional LAMP-style server. No official hosted version exists. You run it or you do not use it.

drawnix13.8k★

A whiteboard app for sketching diagrams, mind maps, and freeform notes, runs in the browser, stores everything locally. If you've used Excalidraw and wished it had a few more structured drawing tools (tables, mind map layouts, flowcharts with auto-routing), drawnix is that. Built on a canvas framework called Plait, which handles the rendering. The result feels snappy. You get shapes, connectors, freehand drawing, text, and a mind map mode that auto-lays-out nodes. Everything exports to PNG or SVG. Free to use at drawnix.com. Self-hosting is also free: it's MIT licensed, clone and run. The pricing page mentions a Pro tier but as of now, the free version has no meaningful restrictions, on GitHub and, which is solid for a drawing tool. The catch: it's newer than Excalidraw and tldraw, with a smaller ecosystem. No real-time collaboration yet (that's the obvious Pro feature coming). Plugin support is limited. If you need multiplayer whiteboarding today, Excalidraw with its collaboration server or tldraw are more mature. But for solo diagramming with a clean UI, drawnix is worth a look.

Markdoc8.0k★

Built by Stripe for their docs (stripe.com/docs runs on it), then open-sourced. Everything is free under MIT. No paid tier, no cloud service. It's a parsing library you integrate into your build pipeline. Stripe maintains it alongside their docs infrastructure. There's nothing to host. Markdoc is a library that transforms .md files into a renderable tree. Plug it into Next.js, React, or any framework. The source files are still readable Markdown. The custom tags look like `{% callout %}` rather than `<Component>`, which means non-developers can still edit the docs. Solo developers: if standard Markdown works, you don't need this. Use it when you need variables (`{% $version %}`) or conditional rendering in docs. Small teams: great for maintaining docs with reusable components: define a callout once, use it everywhere. Growing teams: this is built for docs at scale. The catch: smaller community than MDX. If you want React components directly in Markdown, MDX has a bigger ecosystem. Markdoc's advantage is that source files stay readable as plain text. MDX files are basically JSX with Markdown mixed in.

codebase-to-course4.3k★

This Claude Code skill turns any repository into a beautiful, interactive single-page HTML course. Point it at a codebase, and it generates a structured learning experience that walks through the architecture, key files, and how everything connects. Built specifically for non-technical 'vibe coders' who learn by doing and want to understand what they built (or what someone else built). The output is a single HTML file you can share, host, or open locally. No language specified in the repo. It's a Claude Code skill file, not a traditional software project. The catch: the quality depends entirely on Claude's understanding of the codebase. Complex, poorly-documented codebases will produce courses with gaps. And 'single-page HTML' means everything is in one file. Great for sharing, awkward for very large codebases. This is a skill, not a product. It runs inside Claude Code only.

md-editor-v32.5k★

Md-editor-v3 gives you a split-pane editor with preview, toolbar, and syntax highlighting out of the box. Drop it into your Vue app and you have a working editor in minutes. MIT license, TypeScript. Features include live preview, table editing, code block syntax highlighting, emoji picker, image upload hooks, Mermaid diagram support, KaTeX math rendering, and customizable toolbars. Also supports React via a companion library (md-editor-rt). Dark mode included. Fully free. No paid tier, no premium features. Everything (all toolbar options, all rendering modes, all plugins) is included. Solo to large teams: free. It's a component library, not a service. Your only decision is whether it fits your needs. The catch: this is a Vue-first library. The React port exists but has fewer stars and less community attention. If you're on React, there are more mature options (Tiptap, Milkdown, react-md-editor). Also, the documentation is partially in Chinese; the English docs are functional but not comprehensive. If you hit an edge case, you might be reading source code.

rspress2.2k★

Rspress is a static site generator built on Rust-powered tooling (Rspack) that compiles your Markdown into a blazing-fast React site. It's Docusaurus but with build times that don't make you reconsider your career. It uses MDX, supports full-text search out of the box, has i18n, and generates an optimized site with automatic code splitting. The developer experience is solid: hot reload is near-instant because Rspack (the Rust bundler underneath) handles the heavy lifting. MIT. Fully free. No paid tier, no cloud service, no account. Build your docs site and deploy it wherever you want. The catch: it's emerging. The ecosystem is tiny compared to Docusaurus . Fewer themes, fewer plugins, fewer community answers when you get stuck. If you need extensive customization beyond what ships out of the box, you're on your own. And the ByteDance backing (web-infra-dev) means long-term governance isn't community-driven.

retype1.3k★

Retype does that. Point it at a folder of .md files and it generates a searchable, themed site with navigation, syntax highlighting, and a table of contents. Basically, it's "Markdown in, website out." The free tier lets you build a site with up to 100 pages. That covers most small projects. Beyond that, Pro is $149/project or Business is $249/project (one-time, not subscription). The source code is visible on GitHub but the license is proprietary, not open source despite being on GitHub. There's no cloud hosting from Retype: it generates static files you deploy anywhere: GitHub Pages, Netlify, Vercel, your own server. The build step runs locally or in CI. Solo developers: the free tier works for personal projects and small docs sites. Small teams: 100 pages is tighter than you think; once you add API references and guides, you hit it. The $149 one-time cost is reasonable. Growing teams: Business tier adds custom domains for docs, priority support. The catch: it's not open source. The source is on GitHub for transparency, but the license restricts modification and redistribution. If that matters to you philosophically, Docusaurus or VitePress are fully open source alternatives that do the same thing with more setup.

docs709★

This is the documentation site for Prometheus, not Prometheus itself. If you're looking for the monitoring system, you want prometheus/prometheus. This repo contains the source files for prometheus.io, the website that explains how to use Prometheus. That said, if you're contributing to Prometheus documentation or want to run the docs site locally for reference, this is what you'd clone. It's built with Hugo and TypeScript, hosted at prometheus.io. The catch: this is a documentation repo with . It's not a tool you deploy or use in production. If you ended up here looking for the actual monitoring system, head to prometheus/prometheus, that's the 56K-star project you want.