unbrowser by Unchained MCP server

unbrowser

The cheap browser pass for agents. One native binary. No Chrome.

Official MCP Registry identity: mcp-name: io.github.protostatis/unbrowser

unbrowser is a stateful, non-visual web runtime for agents. It sits between curl/WebFetch and a real browser: it retains cookies and DOM state, returns queryable element refs, handles links and HTML forms, detects challenge and SPA signals, and can run bounded QuickJS page scripts when static HTML is not enough.

Default navigate is a fast static/SSR pass. Set exec_scripts: true only when you need bounded QuickJS execution. Heavy SPAs, pixels, V8 fidelity, extensions, and interactive anti-bot challenges belong in a real Chrome tier.

Try the live public-web demo before installing. It accepts only the fixed public source sets shown on the page; do not send private data, cookies, or authenticated tasks through it. A shared Streamable HTTP MCP endpoint is available at https://unchainedsky.com/unbrowser-mcp for public smoke tests; production sessions should use a local install.

Use unbrowser only on sites, accounts, and data you are permitted to access. Challenge detection and cookie import do not grant permission to bypass access controls or site terms. Treat session cookies as credentials: keep them local, scope them to the authorized task, and never send them to the public demo.

Pick the right tier

Use unbrowser when HTTP alone is too dumb and a full browser is too expensive. When the page needs Chrome, the output tells the agent to escalate rather than pretending compatibility it does not have.

Quick start

Docker — Linux amd64/arm64, ~13 MiB pull

docker pull ghcr.io/protostatis/unbrowser:latest

# One-shot navigation
docker run --rm ghcr.io/protostatis/unbrowser:latest \
  navigate https://example.com --json

# Default mode: MCP over stdio
docker run --rm -i ghcr.io/protostatis/unbrowser:latest

The image is distroless and runs as non-root: no shell, package manager, or persistent state. Pin :vX.Y.Z or an image digest in production.

Python

pipx install pyunbrowser   # recommended on macOS / modern Linux
# or, inside a Python 3.10+ virtual environment:
pip install pyunbrowser

from unbrowser import Client

with Client() as ub:
    ub.navigate("https://news.ycombinator.com")
    for link in ub.query(".titleline > a")[:3]:
        print(link["text"], link["attrs"]["href"])

On macOS, /usr/bin/python3 is 3.9 and cannot install the wheel; use pipx or a Homebrew Python. The PyPI distribution is pyunbrowser, while the import and executable remain unbrowser.

MCP

{
  "mcpServers": {
    "unbrowser": {
      "command": "unbrowser",
      "args": ["--mcp"]
    }
  }
}

Minimal surface: add "--mcp-profile", "minimal" to expose only navigate/query/extract/help and let the agent discover the rest via help(topic). The Python wrapper ships a 3-tool smart server (search/open/help) as the unbrowser-smart console script.

Docker MCP configuration

Shortened. The full README is on GitHub.