Brimp

Brimp is a unified browser interface for agents. It has two builtin runtime

Brimp is a lightweight, headless browser for agents. It combines JavaScriptCore with Blitz's DOM implementation and curl-impersonate as the network stack.

Documentation: docs.brimp.ai

Key references:

• CLI commands
• CDP support matrix and Playwright connection
• JavaScriptCore integration and direct page evaluation
• Subsystem implementation

Why

Getting the html with curl_cffi is easy, but oftentimes, you need to render the page with JavaScript, and anti-bot services are consistently probing if you have a valid browser environment, hence JavaScript fingerprints.

Brimp, short for browser-impersonate, tries to add the missing JS and DOM layer for curl_cffi.

Features

• Page rendered with DOM and JS, so you don't get the empty html placeholder.
• curl-impersonate as the network stack, providing perfect Ja3/TLS, http 2&3 fingerprints.
• Provides a CDP worker for the Brimp controller (brimp serve).
• Much faster than playwright with Chromium, on par with popular alternatives.
• Pre-compiled, so you don't have to compile on your machine.
• MIT licensed.

	chromium	camoufox	cloakbrowser	lightpanda	obscura	brimp
JS & DOM	✅	✅	✅	✅	✅	✅
http/3	✅	✅	✅	❌	❌	✅
CDP	✅	✅	✅	☑️1	☑️1	☑️1
screenshot	✅	✅	✅	❌	✅	✅
JS engine	V8	SpiderMonkey	V8	V8	V8	JSC
open source	✅	✅	❌	☑️2️	✅	✅
ja3 fingerprints	☑️3️	☑️3️	☑️3️	❌	✅	✅
fast?	🐢	🐢	🐢	🐇	🐇	🐇

Notes:

1. Only a common subset was implemented.
2. Lightpanda is under the AGPL license.
3. Fingerprints are fixed to the browser version

Install

For humans:

curl https://brimp.ai/install.sh | bash

For agents:

Paste this prompt:

Install this tool: https://github.com/lexiforest/brimp

You can also download the prebuilt binary tarballs from github release page.

Usage

CLI

The CLI launches and manages its browser workers. Select a lite or WebKit worker with --worker-path or BRIMP_WORKER_PATH; use --cdp to launch a WebSocket CDP worker such as Chrome. The controller discovers and connects to its child automatically. For a lite worker:

export BRIMP_WORKER_PATH=/path/to/lite-worker

Check the worker, extract a live page, evaluate JavaScript, or capture a PNG:

brimp doctor
brimp fetch https://example.com --output example.md
brimp fetch https://example.com --eval 'document.title'
brimp fetch https://example.com --output example.png --full-page
brimp fetch https://example.com --persona crates/worker/src/persona/example.json --eval 'navigator.userAgent'

With CDP clients

Start the Brimp controller (brimp serve) with lite-worker, then connect with playwright-core:

brimp serve \
  --worker-path /path/to/lite-worker \
  --headless --window-size=1280,720 --port=9222

import { chromium } from 'playwright-core'

const browser = await chromium.connectOverCDP('http://127.0.0.1:9222')
const context = browser.contexts()[0] ?? await browser.newContext()
const page = await context.newPage()
await page.goto('https://example.com')
console.log(await page.evaluate(() => document.title))
await browser.close()

Brimp implements the CDP subset needed by this workflow, not the complete Chrome DevTools Protocol. Puppeteer is also supported through puppeteer.connect({ browserURL: 'http://127.0.0.1:9222' }).

Building from source

Prerequisites

Source builds dynamically link JavaScriptCore and curl-impersonate. Set BRIMP_JSC_LIB_DIR and BRIMP_CURL_LIB_DIR to their platform-specific library directories. See the native prerequisites for SDK preparation and library layouts.

Development

Architecture

The implemented runtime supports:

• static HTML, JavaScript DOM mutation, style/layout queries, and CPU PNG screenshots;
• HTTP(S) navigation through a transport-neutral ResourceLoader;
• linked CSS, common raster images, classic inline/external scripts, defer, and async;
• parser pausing around blocking scripts;
• events, timers, microtasks, Promise-based fetch, cookies, Location, and Navigator.

The canonical owner-thread automation API is exposed through:

• the brimp CLI for evaluation and screenshots;
• the framed CDP worker used by the Brimp controller (brimp serve).

The lite worker delegates browser operations to runtime. The CLI and controller communicate with worker processes over framed CDP and never initialize the browser runtime themselves.

CI

The project is tested and built automatically on GitHub Actions. All PR must pass the automatic tests.

Testing

cargo build -p brimp-controller -p brimp-lite-worker
cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings