Overview

Yes, you can use the npm package you already know, and you import it exactly the way you already do.

TypeScript

import express, { type Request, type Response } from 'express';
import { readFileSync } from 'node:fs';

const html = readFileSync('index.html', 'utf-8');

const app = express();
app.get('/', (_req: Request, res: Response) => res.type('html').send(html));
app.listen(8080);

That file builds and runs on all four runtimes, and nothing in it mentions @gjsify. What changes is what the imports resolve to. An --app gjs build rewrites node:fs to @gjsify/fs, backed by Gio.File, and every node:* import inside express and its dependencies goes the same way. An --app node build leaves them alone, because Node, Bun and Deno ship those builtins themselves. How It Works has the details.

Install a package from npm

Install it like any other dependency. Each installer writes the module layout its own runtime resolves against, so use the one your project is set up for.

Install express

Terminal

gjsify install express

Terminal

npm install express

Terminal

bun add express

Terminal

deno add npm:express

You never add @gjsify/fs, @gjsify/http or any other polyfill by hand. @gjsify/cli depends on two umbrella packages, @gjsify/node-polyfills and @gjsify/web-polyfills. Once the CLI is a devDependency of your project, and every scaffold from gjsify create has it, the whole polyfill set is already resolvable. Name an umbrella yourself only if you build without @gjsify/cli in your dependency tree.

Node.js builtins and Web APIs

Import builtins with the node: prefix, or the bare form (import fs from 'fs') that older dependencies use. Node.js Modules lists each one and what backs it. fetch, WebSocket, crypto.subtle and ReadableStream are globals, not imports, and Web APIs lists everything available that way.

When you do write @gjsify/... in an import

These are the things that have no standard bare specifier:

• GTK bridge widgets. @gjsify/canvas2d, @gjsify/webgl, @gjsify/video and @gjsify/iframe export widget classes you mount into a GTK tree. See DOM & Graphics.
• The Adwaita design system on the web. @gjsify/adwaita-web gives you Adwaita as Web Components for --app browser builds. See the Adwaita gallery.
• The native app shell. @gjsify/adwaita-app wraps the Adw.Application boilerplate. See Build a native Adwaita app.
• The renderer host. @gjsify/gtk-host is the element model the Solid, Vue and React renderers bind to, so you describe a GTK window instead of assembling it. Its /style subpath answers a utility class or a style object with GTK CSS, a widget property, or an intent. See UI Frameworks and Styling on GTK.
• React Native’s vocabulary. @gjsify/react-native is the package a bundler aliases react-native to: <View>, <Text>, <Pressable> over the same host, with a support table that gives every name it does not implement a status and a reason. See React Native.

Install a GJSify package

Terminal

gjsify install @gjsify/canvas2d @gjsify/adwaita-app

Terminal

npm install @gjsify/canvas2d @gjsify/adwaita-app

Terminal

bun add @gjsify/canvas2d @gjsify/adwaita-app

Terminal

deno add npm:@gjsify/canvas2d npm:@gjsify/adwaita-app

What is implemented

Category	Packages	What you get
Node.js Modules	one per builtin, plus meta packages that pull a whole set in	fs, net, http, crypto, stream, events, sqlite, ws and more
Web APIs	one per standard, plus meta packages and the native Vala bridges some opt into	fetch, XMLHttpRequest, WebSocket, WebRTC, WebAudio, Streams, DOMParser, MessageChannel, WebAssembly and more
DOM & Graphics	the DOM element model, plus one bridge per GTK-backed element	Canvas 2D, WebGL, DOM elements, and the GTK-backed Canvas / WebGL / Video / IFrame widgets
Framework	renderer host, React Native layer, app shell plus tooling	@gjsify/gtk-host and its style partition, @gjsify/react-native, @gjsify/adwaita-app, storybook, devtools
Adwaita for the browser	the widget set, its headless core, and the assets and storybook renderer beside them	@gjsify/adwaita-web, @gjsify/adwaita-core, @gjsify/adwaita-fonts, @gjsify/adwaita-icons, @gjsify/adwaita-storybook
Reverse bridge	1	@gjsify/node-gi, GObject-Introspection on Node.js, Bun and Deno
Forward bridge	1	@gjsify/napi, native Node.js N-API .node addons in GJS

Coverage says how much of each row is implemented, module by module, rendered from generated data. No percentage is repeated here by hand: a rendered list cannot disagree with itself, and a number typed beside it on another page has nothing holding it.

DOM ↔ GTK Bridges

Standard DOM elements, rendered natively

App code uses standard HTML elements. Each bridge translates the DOM lifecycle to a GTK widget — Cairo for 2D, OpenGL via libepoxy for WebGL, GStreamer for video, WebKit for iframes.

HTMLCanvasElement (2D) → Gtk.DrawingArea

@gjsify/canvas2d Cairo + PangoCairo

HTMLCanvasElement (WebGL/WebGL2) → Gtk.GLArea

@gjsify/webgl Vala/gwebgl + libepoxy

HTMLIFrameElement → WebKit.WebView

@gjsify/iframe WebKit 6.0

HTMLVideoElement → Gtk.Picture

@gjsify/video GStreamer + gtk4paintablesink

Native Vala bridges

Terminal @gjsify/terminal-native

Posix.isatty + ioctl TIOCGWINSZ + termios for @gjsify/tty

Shared ArrayBuffer @gjsify/sab-native

Cross-process shared memory + futex atomics for @gjsify/worker_threads

TLS @gjsify/tls-native

Direct OpenSSL access for @gjsify/tls

HTTP-Soup @gjsify/http-soup-bridge

Native Soup integration helpers for @gjsify/http

HTTP/2 @gjsify/http2-native

nghttp2 bridge for h2c, push streams, flow control

WebRTC @gjsify/webrtc-native

GLib.Idle signal marshalling for webrtcbin's streaming-thread callbacks

Will my dependency work?

It depends on what it reaches for, and two checks tell you before you try.

• The module list. If your dependency only touches modules marked Full on the Node.js and Web APIs pages, it will almost certainly run.
• The integration suites. Coverage lists the real npm packages whose own test suites run unmodified against @gjsify/*: axios, socket.io, yargs, execa, fast-glob, cosmiconfig, webtorrent, acorn and more. Express, three.js and Excalibur.js run as full showcases.

If a build fails on a missing global, the error names the identifier and How It Works shows the one-flag fix.

Where to go next

• Node.js Modules, every builtin and what backs it
• Web APIs, the standards that work as globals
• DOM & Graphics, canvas, WebGL, video and iframes inside GTK windows
• Versioning, how to upgrade @gjsify/* safely
• Runtimes, the same source on GJS, Node.js, Bun, Deno, the browser and mobile