Browser Use, built on Pi Mono. In TypeScript.

Pi Mono + a persistent V8 REPL + raw CDP. The agent writes JavaScript, controls Chrome, and builds the helpers it needs as it goes.

Your task → Pi Mono → persistent V8 REPL → raw CDP → Chrome
                ↑                                    │
                └──────── AX tree + screenshots ──────┘

The programmability of Browser Harness, with sessions, saved logins, streaming and typed results. One SDK you can put in your app.

npm install @browser_use/pi
# or: pnpm add @browser_use/pi
# or: bun add @browser_use/pi
export OPENROUTER_API_KEY=...
export BROWSER_USE_API_KEY=...

import { Browser, BrowserUse } from '@browser_use/pi';

const agent = await BrowserUse.create({
  model: 'openrouter/openai/gpt-5.6-luna',
  reasoning: 'xhigh',
  browser: Browser.cloud({ apiKey: process.env.BROWSER_USE_API_KEY! }),
  workspace: './work',
});

try {
  const result = await agent.run('Find the top story on Hacker News.');
  console.log(result.status, result.text);
  await agent.followUp('Summarize the comments.');
} finally {
  await agent.close();
}

Save as agent.ts. Run with node agent.ts or bun agent.ts. Uses Browser Use Cloud; no local Chrome installation needed.

Node 22.19+ · Bun 1.3.14+. Bun also needs Node for the V8 worker.

• Models: upstream Pi's model catalog and transports, with custom providers supported. Model capabilities and provider access vary. Models
• Sessions: follow-ups, saved logins, persistent workspaces, cloud browsers or your own Chrome. Sessions
• Ultrafast: mode: 'ultrafast' prints a compact accessibility-tree state and acts on its ids, waiting only briefly after each action, for interaction-heavy tasks.
• Control: streaming, hooks, typed results and compaction. Cap steps, time or cost and keep partial work. API
• Show the work: interaction highlights, recordings and GIF exports. Examples

Quickstart · Browser primitives · Python · Historical benchmarks

JavaScript runs in a killable worker with filesystem and network access. Use an isolated machine for untrusted tasks. Anonymous run counters are enabled; disable with telemetry: false or DO_NOT_TRACK=1. Telemetry

npm test
npm run check
npm run docs:build
npm run test:python