Mozilla's MCP server for Firefox: your agent browses and fills in forms, or inspects pages with the console, network, debugger and profiler.
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About
Mozilla's own MCP server lets your agent use Firefox. It has two main uses: agentic browsing, where your agent reads pages, fills in forms and goes through multi-step flows on websites, and agent-assisted web development, where it loads the page you're working on and inspects it with Firefox's developer tools. What you can do with it - Open, navigate and switch between pages, and read a page's text - Take a snapshot of the page, then click, hover, type, drag, upload files and fill in whole forms - Take screenshots of a page or a single element, print a page to PDF and record screencasts - List and inspect network requests, and read console messages - Run JavaScript in the page, read script sources and set logpoints - Start and stop the Firefox profiler - Install and remove web extensions, and handle downloads and dialogs - Drive Firefox for Android on a connected device How it connects It runs on your machine with npx @mozilla/firefox-devtools-mcp@latest, and needs Node.js 20.19 or later and Firefox 100 or later. Mozilla documents setup for Claude Code and Codex, and says it works with Claude Desktop, Cursor, Cline and other MCP clients. It's also a Gemini CLI extension, which starts it with the developer tools turned on. Flags let you run Firefox headless, set the window size, pick a Firefox profile or attach to a Firefox you already have open. Choose what it can do --tool-preset picks which tools it exposes: slim to browse and interact with pages, basic (the default) for regular browsing, and developer to add network, console, debugging and profiler tools. --tools lets you list exact modules instead. Good to know - Mozilla advises a dedicated Firefox profile, since the agent can reach whatever the browser can, including cookies and saved sessions. - Pages can contain text written to steer the agent, so stick to sites you control or trust. - The default basic preset includes evaluate_script; slim drops it. - Android mode wipes all data of the Firefox app it drives before every session.
Once it’s added
“Open example.com and fill in the signup form with these details.”
“Load my app at localhost:3000 and tell me what errors show up in the console.”
Before you add it
Reads only
Page text, snapshots and screenshots · Network requests and console messages · Script sources and profiler results
Makes changes · your agent can ask first
Clicks, types and fills in forms on pages · Runs JavaScript in the page · Installs web extensions and saves downloads and output files
From people who use it
Step by step
Plugins people install alongside Firefox DevTools MCP.
No reviews yet. Used Firefox DevTools MCP? Say how it went.
Write a reviewRuns on your machine.
claude_desktop_config.json{
"mcpServers": {
"firefox-devtools-mcp": {
"command": "npx",
"args": [
"-y",
"@mozilla/[email protected]",
"--tool-preset",
"developer"
]
}
}
}Runs on your machine.
Add to VS Codecode --add-mcp '{"name":"firefox-devtools-mcp","command":"npx","args":["-y","@mozilla/[email protected]","--tool-preset","developer"]}'copilot mcp add firefox-devtools-mcp -- npx -y @mozilla/[email protected] --tool-preset developer
Runs on your machine.
Add to Cursor.cursor/mcp.json{
"mcpServers": {
"firefox-devtools-mcp": {
"command": "npx",
"args": [
"-y",
"@mozilla/[email protected]",
"--tool-preset",
"developer"
]
}
}
}Runs on your machine.
claude mcp add firefox-devtools-mcp -- npx -y @mozilla/[email protected] --tool-preset developer
Runs on your machine.
codex mcp add firefox-devtools-mcp -- npx -y @mozilla/[email protected] --tool-preset developer
Runs on your machine.
~/.gemini/config/mcp_config.json{
"mcpServers": {
"firefox-devtools-mcp": {
"command": "npx",
"args": [
"-y",
"@mozilla/[email protected]",
"--tool-preset",
"developer"
]
}
}
}Runs on your machine.
gemini extensions install https://github.com/mozilla/firefox-devtools-mcp
Runs on your machine.
Runs on your machine.
opencode mcp add firefox-devtools-mcp -- npx -y @mozilla/[email protected] --tool-preset developer
Runs on your machine.
~/.hermes/config.yaml{
"mcp_servers": {
"firefox-devtools-mcp": {
"command": "npx",
"args": [
"-y",
"@mozilla/[email protected]",
"--tool-preset",
"developer"
]
}
}
}FIREFOX_HEADLESSOptionalSet to true to run Firefox without a visible window.START_URLOptionalURL to open when the server starts.Scanned and passed · checked 8 h ago
Plugins people install alongside Firefox DevTools MCP.
Hand web tasks to a Browser Use agent in a cloud browser: it browses sites, fills in forms and pulls out the data you asked for.
ByteDance's local MCP server that lets your agent drive a real browser: open pages, click, fill in forms, read pages and take screenshots.
Microsoft's MCP server for browser automation with Playwright: your agent navigates, clicks and fills in pages from structured snapshots.
Plans and builds scraping pipelines with Firecrawl or local Python, and won't hand over the data until it passes a validation check.
Nobody has shared how they use Firefox DevTools MCP yet.
“Which network requests failed when this page loaded?”
“Take a full-page screenshot of the pricing page.”
“Profile this page while it loads and tell me what's slow.”
“Add a logpoint to the checkout script and show me what it logs.”
Nothing new reaches your agent until a person has looked at it.
Scanned on every change, and again when our rules improve.
CursorSupported
Claude CodeSupportedTell us and a person on the trust team will look at it. Or email [email protected].
Security scan
Passed
Safe to install in every agent it supports. Runs on your machine.