Mastro

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.

Minimal yet powerful

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 bloat

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.

Documentation

Extensions

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:
Install 3rd-party packages like:
- Kysely – type-safe SQL query builder
- Sveltia CMS – git-based CMS

Join the community

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.