No dependencies. No build step. Just a simple web framework.
Mastro is a web framework and static site generator for people who care about their users and web standards. It’s simple, pragmatic, and implemented in just ~800 lines of TypeScript.
Use JavaScript/TypeScript’s mature tooling to build fast server-rendered websites. Instead of drowning in layers of abstractions, work directly with the browser and your JavaScript runtime – Node.js, Deno, Bun, or Workers.
Get started Docs ☆ Mastro on GitHub
As seen on the Internet!
Mastro's source code is extremely readable.
– Erik Onarheim
A library worth checking out!
– Jared White
Minimal yet powerful
- Static site generation (SSG) – ideal for blogs, marketing sites or webshops that are fast.
- Server-side rendering (SSR) – use Mastro’s composable primitives as a full-stack framework.
- Everything is a route: serve HTML, JSON REST APIs, CSS, and images with the same API.
- Adopt incrementally: use templates in your existing codebase or migrate route by route.
No dependencies, no build step
- No bloat: implemented in just ~800 lines of TypeScript, Mastro is fast.
- No build step (until you add one): your code ships exactly how you wrote it.
- No JavaScript (until you ship some): create fast content-driven MPA websites.
- No dependencies: use web standards instead of keeping up with the frontend treadmill.
- No VC-money: no eventual enshitification – selling is none of our business.
- No lock-in: swap out Mastro later or fork it – it’s only ~800 lines.
// Respond to a HTTP GET with plain text
export const GET = () => {
return new Response("Hello World");
}
import { jsonResponse } from "@mastrojs/mastro";
import { addComment } from "../models/comments.ts";
// Respond to a HTTP POST with JSON
export const POST = async (req: Request) => {
const data = await req.json();
const comment = await addComment(data);
return jsonResponse(comment);
};
import { readMarkdownFiles } from "@mastrojs/markdown";
import { html, htmlToResponse } from "@mastrojs/mastro";
import { Layout } from "../components/Layout.ts";
// Respond with HTML
export const GET = async () => {
const posts = await readMarkdownFiles("posts/*.md");
return htmlToResponse(
Layout({
title: "My blog",
children: posts.map((post) => html`
<p>${post.meta.title}</p>
`)
})
);
};
import { html, type Html } from "@mastrojs/mastro";
interface Props {
title: string;
children: Html;
}
export const Layout = (props: Props) =>
html`
<!DOCTYPE html>
<html lang="en">
<head>
<title>${props.title}</title>
</head>
<body>
<h1>${props.title}</h1>
${props.children}
</body>
</html>
`;
More examples Source of this website
Easy for beginners
Put your first website live without installing anything on your computer: The popular VS Code editor also runs in the browser.
Start with learning HTML and CSS. Then build a static blog and a to-do list app with JavaScript. Finally, serve a REST API.
Powerful for experienced developers
I’ve seen things you wouldn’t believe. Megabytes of JavaScript on fire in the browser. I watched towers of complex abstractions collapse upon themselves. All those websites will be lost in time, like tears in rain. Time to let them die.
Install Mastro Docs ☆ Mastro on GitHub
Fast for everyone
Great UX: websites built with Mastro are fast – even on low-end devices on 3G.
Performance- Accessibility
- SEO
Great DX: dev server starts instantly, and SSG is fast – e.g. for 500 markdown files:
| Mastro | 0.5s | 🏁 |
| 11ty | 0.7s | |
| Astro | 2.2s | |
| Next.js | 16.3s |
Interactive user interfaces
For client-side interactivity in the browser, either use plain JavaScript, or add a library like HTMX, Alpine, Unpoly, ArrowJS, or Reactive Mastro, which allows you to share templates with the server.
A foundation to build upon
The minimal Mastro core package doesn’t come “batteries included”, but it’s built to be extended.
Extensions / plugins
- Tiny libs in the
@mastrojsnamespace: - Install 3rd-party packages like:
- Kysely – type-safe SQL query builder
- Sveltia CMS – git-based CMS
Escape the frontend treadmill
Most JavaScript frameworks and complex build systems were designed to solve problems that no longer exist.
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.