Usable Browser Agent (free) by STS Ky

Usable Browser Agent lets your AI agent act in your real Firefox browser, not a throwaway profile. You log in once and the agent works on real sites as you.

Free tier

This is the free personal/evaluation tier: the same single-session extension as the commercial build, licensed for personal, non-commercial use and for evaluating the product before buying. Commercial use (in or for a business, in paid client work, or inside a commercial product or service) requires the commercial license, a one-time $39 purchase at https://savvytechsphere.com/usable-browser-agent. There is no license key in the product and nothing checks for one; the tiers differ only in the license grant and the add-on identity.

How it works

The extension is one half of the product. The other half is a small MCP server that runs on your own machine. Your agent (Claude Code, Codex, or any MCP client) talks to that server, and the server relays commands to this extension over a WebSocket on 127.0.0.1. The bridge runs locally. Browser snapshots are sent to the configured AI model so it can complete the task. Without the local server the extension does nothing; the toolbar popup shows whether it is connected. Get the free server (with a one-command installer and docs) from the public repository: https://github.com/Savvy-Tech-Sphere/usable-browser-agent-free (clone it, or download the zip from its Releases page), then run node bin/uba-install.mjs to register it with Claude Code or Codex.

What the agent can do

• Read pages as an accessibility-style snapshot with stable element refs
• Click, type, select, scroll, hover, drag, and fill forms
• Navigate, manage tabs, take screenshots, save the page as a PDF, and download files
• Read and write the clipboard, watch network activity, and handle dialogs

Credential safety, each point backed by an automated test

• You store credentials in a local vault file. The agent logs you in by alias and never receives the credential value.
• Credentials are refused on hosts the alias does not allow, so a lookalike domain cannot phish a stored login.
• Secret values are scrubbed from every tool result the agent reads, and screenshots are blocked while a credential is visible on the page.

Privacy

The extension collects no data. There is no analytics, telemetry, or remote logging, and it executes no remotely hosted code. It talks only to the server process on your own machine over 127.0.0.1. Page content, screenshots, and clipboard data go to your connected AI agent and its configured model. Nothing is sent to Savvy Tech Sphere.

Setup

Setup takes a few minutes: install this extension, run the local MCP server, and point your agent at it. The server and the setup instructions are provided from the product page: https://savvytechsphere.com/usable-browser-agent. Requires Firefox 142 or later.

Known limits

The agent acts on the currently active tab, so keep the tab you want it to use focused. The eval tool runs in the page context, so pages with a strict Content Security Policy can block it.