ghostty-web is an MIT-licensed TypeScript library that brings Ghostty's WASM-compiled VT100 terminal emulator to the browser behind an xterm.js-compatible API, built for web developers who want a correct terminal in the page without abandoning their existing xterm.js integration.

What it is

ghostty-web is a browser terminal library published to npm as ghostty-web. It ships as a WASM-compiled parser taken from Ghostty — the same code that runs the native Ghostty application — rather than a reimplementation, and it carries zero runtime dependencies in a bundle of roughly 400KB of WASM. The project is written in TypeScript under the MIT licence, is filed in this registry under Productivity & Utilities / Browsers & Extensions, and carries the topics browser, ghostty, library, and terminal. It was originally created for Mux, Coder's desktop app for isolated, parallel agentic development, but the README states it is designed to be used anywhere.

The concrete problem it solves is the hand-written terminal emulation inside xterm.js, the renderer behind VS Code, Hyper, and countless web terminals. xterm.js reimplements terminal emulation in JavaScript, so every escape sequence, edge case, and Unicode quirk is coded by hand and inevitably develops gaps. ghostty-web replaces that JavaScript emulator with Ghostty's battle-tested parser while keeping the calling convention the same, so a project migrates by changing one import: @xterm/xterm becomes ghostty-web. It therefore sits in the browser terminal ecosystem as a drop-in substitute for the rendering and parsing layer, not as a full terminal application.

Key capabilities

• API compatibility with xterm.js through init, Terminal, term.open(), term.onData(), and term.write().
• WASM-compiled parser built from Ghostty's source, sharing the emulator that runs the native app.
• Proper grapheme handling for complex scripts such as Devanagari and Arabic, where xterm.js has rendering issues.
• Full support for the XTPUSHSGR/XTPOPSGR escape sequences, which xterm.js does not support.
• Zero runtime dependencies with a roughly 400KB WASM bundle.
• One-line migration path: change the import from @xterm/xterm to ghostty-web.
• A runnable demo, npx @ghostty-web/demo@next, that starts a loopback-only HTTP server with a real shell on http://127.0.0.1:8080, protects /ws with a per-run same-origin token, and rejects cross-origin WebSocket handshakes.

Who uses it and how

• Mux, Coder's desktop application for isolated, parallel agentic development, is the original consumer of the library.
• Web terminal projects already built on xterm.js swap the import and keep their existing Terminal configuration and data plumbing.
• Developers evaluating the library run npx @ghostty-web/demo@next locally, which works best on Linux and macOS, to get a real shell in the browser.
• Deployments that serve the demo through extra hostnames or a wildcard bind such as HOST=0.0.0.0 must set GHOSTTY_ALLOWED_HOSTS=host1,host2; HOST= binds elsewhere.
• A live demo runs on an ephemeral VM at ghostty.ondis.co, hosted by Greg from disco.cloud.

Getting started

Install with npm install ghostty-web, then await init() before constructing a Terminal. For a working client and server example, run npx @ghostty-web/demo@next or read the demo source.

How it compares

Within the tools named in the facts, ghostty-web positions itself directly against xterm.js: it keeps the API but swaps the emulation core for Ghostty's, gaining complex-script rendering and XTPUSHSGR/XTPOPSGR support. It is also distinct from Ghostty itself, since Ghostty is the native application whose parser this library compiles to WASM. No paid products are listed as being replaced.

When to use it — and when not to

Anyone who runs the demo must understand that it starts a real local shell, and the README advises avoiding remote exposure unless that risk is understood. Building from source requires Zig and Bun and applies patches/ghostty-wasm-api.patch to Ghostty's tree via bun run build, so contributors take on a patch-maintenance burden, albeit one the authors expect to shrink as libghostty matures and a native Ghostty WASM distribution becomes consumable. Teams wanting a frozen emulator with no upstream tracking should not pick it.

npm install ghostty-web

import { init, Terminal } from 'ghostty-web';

await init();

const term = new Terminal({
  fontSize: 14,
  theme: {
    background: '#1a1b26',
    foreground: '#a9b1d6',
  },
});

term.open(document.getElementById('terminal'));
term.onData((data) => websocket.send(data));
websocket.onmessage = (e) => term.write(e.data);

bun run build