Firefox CLI is my new project - a CLI interface that lets your agent control your real Firefox session.

It’s a full equivalent of Agent Browser with the same capabilities, but for Firefox - and with a number of improvements.

Why it’s better

First, you install the extension once and for all. The extension ships right alongside the CLI: install it, grant access, forget about it. Unlike Chrome, where you have to grant connection permissions every half hour and manage debugging sessions - here it’s one button and full control.

Second, your agents can now create their own separate windows and request your permission to connect on their own.

In everything else, Firefox CLI mirrors Agent Browser: token-efficient operation via short IDs, running arbitrary scripts, keypresses, input emulation, form filling, and full tab and window management of your real session - where you’re already logged in.

Why I built it

I used the Comet browser for a long time (on my promo subscription to Perplexity), but it started to let me down. More unnecessary features and ads crept in, it got slower. But the main thing - using Comet as an actual browser during development is extremely inconvenient: there’s music you can’t turn off, a broken onboarding that was never fixed after months of back-and-forth with support, and a poorly functioning CDP.

I switched back to Firefox as my main browser, but losing the ability for agents to control my browser was a huge blow to my workflow. No automation for filling out boring freelance forms, no proper web app testing. I went looking for alternatives, but nothing like Agent Browser for Firefox simply existed. And here’s the result :)

Installation

1. Install the CLI:

npm install -g firefox-cli

2. Install the Firefox extension:

firefox-cli setup

3. Install the skill for agents:

Claude Code

/plugin marketplace add respawn-llc/claude-plugin-marketplace
/plugin install firefox-cli@respawn-tools

Codex

$skill-installer install https://github.com/respawn-llc/firefox-cli/tree/main/skills/firefox-cli

General

npx skills@latest add respawn-llc/firefox-cli

The project was built by Builder autonomously over 62 hours of continuous work.