Mastro

The simplest web framework and site generator you've ever seen.

Website | Try Mastro online

Static site generation and on-demand rendering of HTML or JSON – it all works exactly the same in Mastro: a file-based router, and a handful of composable functions to return standard Response objects. No magic, no config – just focus on building awesome websites.

No bloat: written in just ~700 lines of TypeScript, Mastro is a framework distilled to its essence.
No client-side JavaScript (until you add some): create MPA websites that load blazingly fast.
No bundler (until you add one): your code arrives in the browser exactly how you wrote it.
No magic: use normal <img> and <a> tags referencing HTTP-first assets.
No VC-money: this forces us to stay lean and prevents eventual enshitification.
No hosting offer: selling a service is not what we're interested in.
No update treadmill: we use web standards instead of relying on many dependencies.

How to run

In the browser

Build and deploy your website to GitHub Pages for free – without installing anything: Get started on GitHub.dev

Command line

If you prefer the command line, or need to run a server, install either Deno (recommended), or Node.js.

Deno

After installing Deno, either use the Mastro template for Deno or run:

deno run -A npm:@mastrojs/create-mastro@0.0.8

Node.js

Either use the Mastro template for Node.js or run:

pnpm create @mastrojs/mastro@0.0.8

(npm and yarn also work, but pnpm is recommended.)

Bun

Either use the Mastro template for Bun or run:

bun create @mastrojs/mastro@0.0.8

Deploy to production

To deploy your website, see Different ways to run Mastro.

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. Usually, it's just a single file wrapping a carefully chosen external dependency.

@mastrojs/markdown – generate HTML from markdown
@mastrojs/images – transform images (resize, compress, etc)
@mastrojs/feed – generate an Atom feed
Reactive Mastro – a tiny client-side reactive GUI library for MPAs

Join the community / contribute

It's still early days. But we're looking to build an inclusive community of all kinds of people, united by a shared passion for crafting websites and learning new things.

If you have any questions, or want to talk about future plans, please start a GitHub Discussion.

Something not working as expected or confusing? That's a bug: please open a GitHub issue.