xterm.js

xterm.js is a frontend component that lets web applications deliver complete, interactive terminal experiences directly in the browser. It emulates a real terminal — handling curses-based apps, mouse events, rich Unicode, and VT sequences — while shipping with zero runtime dependencies in its core.

Battle-tested inside VS Code, Hyper, and Tabby, xterm.js pairs an ergonomic Terminal API with an optional GPU-accelerated WebGL renderer and a modular addon system, making it the de-facto standard for browser-based terminals, SSH clients, and cloud IDEs.

What You Get

• A dependency-free core Terminal class that renders and emulates a VT100-compatible terminal in any modern browser
• An optional GPU-accelerated WebGL renderer addon for high-performance drawing
• A modular addon ecosystem (fit, search, web-links, attach, serialize, clipboard, unicode, ligatures, and more)
• A headless build (@xterm/headless) that runs terminal state tracking in Node.js without a DOM
• A fully typed public API via bundled TypeScript declarations, shipped as both CommonJS and ES modules

Common Use Cases

• Building browser-based SSH and shell clients that stream a remote pty to the user
• Embedding an integrated terminal inside a cloud IDE, code playground, or developer tool
• Providing container and VM management consoles in web dashboards
• Rendering live command output and interactive REPLs in web apps

Under The Hood

Architecture The codebase is layered into three cleanly separated units under src/: common/ holds the environment-agnostic terminal core (the VT parser in common/parser, InputHandler.ts, buffer management in common/buffer, and a service layer via CoreTerminal.ts), browser/ adds DOM-facing concerns (CoreBrowserTerminal.ts, renderers, selection, links, accessibility) and headless/ provides a DOM-free build. A service-oriented design with dependency injection wires these layers, and functionality is extended through a public addon interface (Terminal.loadAddon) with each addon isolated as its own npm workspace under addons/.

Tech Stack Written almost entirely in TypeScript (~96%), the core library ships with zero runtime dependencies. It builds with the TypeScript compiler plus esbuild and webpack for bundling, publishes dual CommonJS/ESM outputs, and is linted with oxlint and ESLint. Rendering uses the browser DOM with an optional WebGL2 canvas path provided by the webgl addon.

Code Quality Quality is high: unit tests (*.test.ts) sit alongside source across common/ and browser/, and a Playwright-driven integration suite runs against Chromium, Firefox, and WebKit. Type-aware linting is enforced with --max-warnings 0, naming conventions are checked by a dedicated ESLint config, and a benchmark harness guards performance regressions.

API Design The public API is deliberately small and ergonomic — new Terminal(), open(element), write(data), onData(), and loadAddon() cover most needs, letting developers get a working terminal in a handful of lines. The full surface is documented in a well-maintained TypeScript declaration file (typings/xterm.d.ts), with experimental APIs clearly flagged, and a demo app plus extensive README examples ease onboarding.