umbra

a chrome extension that lets any llm drive my signed-in browser, not just claude in chrome. pairs on a local key, runs in the background, nothing leaves the machine.

get it on the chrome web store source on github

how it works

it's two pieces: a chrome extension that owns every browser action, and a small companion server on your machine that hands a browser tool surface to your mcp client.

they talk over a websocket on 127.0.0.1, signed with an hmac of a key you generate yourself.

screenshots

a local agent driving Chrome from the terminal
a local agent driving chrome from the terminal
MCP tool calls driving the browser
MCP tool calls driving the browser
Umbra runs in the background without stealing focus
runs in the background without stealing focus
each session owns only the tabs it opened
each session owns only the tabs it opened
local-only pairing on a key you generate
local-only pairing on a key you generate

get it

install the extension from the chrome web store, then set up the companion server:

git clone https://github.com/RobertJLora/umbra
cd umbra/mcp-server
npm install
node cli.js pair

pair prints a key for the extension's options page and a config block for your mcp client. the full walkthrough is on github. the privacy details are here (short version: it collects nothing).