Usable Browser Agent MCP server

Usable Browser Agent (free personal / evaluation tier)

An MCP server plus a browser extension that lets your AI agent (Claude Code, Codex, or any MCP client) drive your real browser, with all your logged-in sessions, instead of a throwaway automated browser. You log in once, by hand, and the agent operates as you.

This repository is the free tier: the same single-session MCP server as the commercial build, licensed for personal, non-commercial use and for evaluating the product before buying. The Firefox extension for it is published on Firefox Add-ons. Commercial use (in or for a business, in paid client work, or inside a commercial product or service) needs the commercial license, a one-time $39 purchase at , which also includes the Chrome build. There is no license key in either tier and nothing checks for one; the tiers differ only in the license grant and the extension identity.

Your passwords stay out of the agent. When the agent logs you in, it passes only a secret

alias, never the value. Credentials live in a local vault, are domain-locked (refused on the

wrong site), and are redacted from everything the agent reads or screenshots. See

docs/CREDENTIAL-SAFETY.md.

How it works

Claude Code / Codex / any MCP client
      |  MCP over stdio
      v
  MCP server (Node, this repo)  --hosts-->  WebSocket  ws://127.0.0.1:8876
      ^                                          ^
      | 53 browser_* tools                       | (extension connects out)
      +------------------------------------------+
                                       Firefox extension (from Firefox Add-ons)
                                       your real profile, your logins -> DOM actions on the active tab

The agent perceives pages through an accessibility/DOM snapshot where every interactive element has a stable [ref=eN] handle, then clicks and types by ref. No coordinate guessing, no vision model required. Everything runs on your machine: MCP over stdio, and the extension talks to the server over a WebSocket bound to 127.0.0.1. Nothing leaves your computer.

The agent always acts on the currently active tab. Keep the tab you want it to use focused.

Get started (about 2 minutes)

Two pieces: this MCP server, which your agent launches, and the Firefox extension, which you install once from Firefox Add-ons.

1. Get the server and run the installer

Needs Node.js 18 or newer and Firefox 142 or newer (macOS first; see docs/INSTALL.md).

npm install -g usable-browser-agent
uba-install

Or from a checkout of this repository:

git clone https://github.com/Savvy-Tech-Sphere/usable-browser-agent-free.git
cd usable-browser-agent-free
node bin/uba-install.mjs        # or: npm run setup

(Prefer a download? Grab the zip from the Releases page, unpack it, and run the same command inside the folder.)

The installer checks Node and the port, installs dependencies, registers the MCP server with Claude Code and/or Codex using this copy's absolute path, runs the smoke test, optionally stores your first login, and prints the macOS permission steps. It is idempotent; re-running it never clobbers an existing config. Pass --non-interactive to accept every default.

2. Install the Firefox extension (one time)

Install Usable Browser Agent (free) from Firefox Add-ons:

The toolbar badge shows off, then ON once the extension connects to the MCP server your agent launched. (The installer also prints these steps, plus the .xpi and Chrome steps that apply to the commercial bundle; for the free tier the Add-ons listing is all you need.)

3. Log in and go

Shortened. The full README is on GitHub.