junyeong-nero/kitsune

Bring your coding agent into Firefox and keep working alongside it.
Kitsune lets AI agents such as Claude Code, Codex, Pi, and OpenCode use the Firefox,
Zen, or LibreWolf browser you already have open. Your sessions, cookies, and
extensions stay where they are, and there is no Playwright, Chromium, or WebDriver
to install. Your own scripts can use it the same way, through the
Python API.
The agent can research in background tabs and prepare form drafts while you keep
using the same browser. You stay with the agent you already use; Kitsune is not a
separate browser or a built-in assistant.
The design follows two principles: the user's browser belongs to the user, and
the agent gets fewer, sharper tools. See Philosophy.
A real screen recording of Claude Code and Zen Browser on the live Google sites, sped up while the agent thinks and zoomed in afterwards ( full 38-second video ).
## Why Kitsune?
Tabs the agent creates open in the background. Kitsune holds writes to a tab
while you are typing or clicking in it, refuses writes that name no tab until
the agent has opened or selected one, and closing one of your own tabs takes a
separate confirmation step. This reduces interference, but OS-level clicks and popups
opened by sites still have focus and input limitations.
You decide how much to delegate. KITSUNEMODE=read, draft, or act limits
both the tools the agent sees and the requests the bridge accepts. Draft mode
lets the agent fill supported fields without click or submit tools, although
sites may still autosave what it types. The default, act, has no such
restriction. See Task modes.
The agent starts with Playwright MCP's 25 core tools. Kitsune's other tools
stay off until you allow them, and the agent can find and call the allowed ones
without restarting its session. See Choosing tools.
With the optional automation capability, an interrupted batch, parallel, or
workflow call can be resumed without resending the writes that already
succeeded. A write with an uncertain outcome needs an observation before it is
retried. Checkpoints are temporary and are lost when the bridge restarts.
## What can it do?
In your browser, the agent can:
Search the web, read pages, and summarize what it finds with links.
Click, type, select options, set sliders, and fill forms, including on sites where
you are already signed in.
Take screenshots or turn page content into text and Markdown.
Keep research and tasks in separate tabs without replacing the page you are
using.
## Benchmark
With the same tasks and tool allowlist, Kitsune v0.7.0 kept the user's tab in
front in 28 of 28 shared-browser tasks, against 2 of 28 for Playwright MCP. On
the tasks both solved, Kitsune cost 0.68 to 0.91 times as much, at about the
same number of tool calls. Each solved 209 of 210 tasks. Each task was run once
with Claude Opus 5.5. Playwright MCP was not designed to share a browser with a
person. See the
v0.7.0 report
and the full reports.
scripts/benchmarkchart.py draws the chart from the report's numbers.
## How is it different?
Kitsune is one of several ways to connect an agent to a browser. Which one fits
depends on the browser you use and the work you want to hand off: