Website | Try Mastro online

No dependencies. No build step. Just a simple web framework.

Mastro is a web framework and site generator for people who care about their users and web standards. It’s is implemented in just ~800 lines of TypeScript.

Use JavaScript/TypeScript’s mature tooling to build fast MPA websites. Instead of going through layers of abstraction, work directly with the browser and your JavaScript runtime – Node.js, Deno, Bun, or Workers.

• Static site generation – ideal for blogs, marketing sites or webshops that are fast.
• Server-side rendering – use Mastro as a full-stack web framework.
• Everything is a route: serve JSON REST APIs, CSS, or images, with the same API as HTML.
• Composable: a router and plain helper functions – it's that simple.

• No overhead: implemented in just ~800 lines of TypeScript with no dependencies.
• No client-side JavaScript (until you add some): create MPA websites that load fast.
• No bundler (until you add one): your code ships exactly how you wrote it.
• No magic: use plain <img> and <a> tags referencing asset routes.
• No VC-money: no eventual enshitification – selling is none of our business.
• No update treadmill: we use web standards instead dependencies.
• No lock-in: swap out Mastro later or fork it – it's only ~800 lines after all.

• Get started
• Mastro Docs
• Mastro Guide to web dev

The core of Mastro is tiny. But to get you started quickly for common use-cases, there is a growing list of extensions that are tailored to be used with Mastro. Often, it's just a single file wrapping a carefully chosen external dependency.

• Tiny libs in the @mastrojs namespace:
  • Reactive Mastro – a tiny client-side reactive GUI library for MPAs
  • markdown to HTML
  • images – resize/compress/etc.
  • og-image – generate images from text
  • feed – generate RSS/Atom feeds
  • atproto – add support for Standard.site
  • api – type-safe REST APIs and clients
  • result – a minimal Result type
• Install 3rd-party packages like:
  • Kysely – type-safe SQL query builder
  • Sveltia CMS – git-based CMS

We’re building an inclusive community, where people of all kinds of backgrounds and experience levels feel welcome and safe, and help each other. A place to ask questions and learn new things.

Please start a GitHub Discussion or join us on our Discord or our Stoat.

Something not working as expected or confusing? We consider that a bug. Please open a GitHub issue.