Provides browser automation capabilities through a Firefox extension, enabling DOM snapshots, console log capture, and page state extraction for web interaction and debugging.
YetiBrowser MCP
YetiBrowser MCP is a fully open-source implementation of the Browser MCP workflow. It links a Node-based MCP server with Chrome/Firefox extensions so Model Context Protocol clients—Codex/Claude Code, Cursor, Windsurf, MCP Inspector, or your own tools—can automate a real browser tab while keeping every byte on your machine and auditable.
Why pick YetiBrowser MCP?
Transparent and hackable – no blob downloads. Inspect, fork, and extend every component.
Local-first – the extension talks only to a localhost MCP server; browsing data never leaves your device.
Cross-browser – shared logic powers both Chrome and Firefox packages (Firefox build is pending better Manifest V3 support, so connection UX may be limited until Mozilla ships full MV3 APIs).
Developer-focused tooling – richer console capture, DOM diffing, page-state dumps, and full-page screenshots built for debugging and QA.
Production-friendly – scripts and docs for packaging, publishing, and integrating with IDE workflows.
Repository layout
packages/shared
– shared TypeScript definitions for messages and tool schemas.packages/server
– the MCP server that bridges MCP clients to a running browser tab.extensions/shared
– shared extension source (background/popup) and assets.extensions/chrome
/extensions/firefox
– per-browser packaging layers.docs/
– workspace commands, publishing checklists, and feature notes.scripts/
– helper utilities such aspackage-extensions.sh
for release zips.
MCP Tools Available
browser_snapshot
– capture an accessibility-oriented snapshot of the current pagebrowser_snapshot_diff
– compare the two most recent snapshots to highlight DOM/ARIA changesbrowser_navigate
– load a new URL in the connected tab and return an updated snapshotbrowser_go_back
/browser_go_forward
– move through history while keeping MCP in syncbrowser_wait
– pause automation for a set number of secondsbrowser_press_key
– simulate a keyboard key press on the focused elementbrowser_click
– click the element identified by a CSS selectorbrowser_hover
– hover the pointer over the targeted elementbrowser_type
– type text (optionally submitting with Enter) into an editable elementbrowser_select_option
– choose one or more options in a<select>
elementbrowser_screenshot
– capture a viewport or full-page screenshot via the DevTools protocolbrowser_get_console_logs
– return recent console output, including errors with stack tracesbrowser_page_state
– dump forms, storage keys, and cookies for the connected pagebrowser_connection_info
– report bridge WebSocket port, connection status, and extension version
MCP Browser Extension Installation
Chrome Browser
Install the latest Chrome Browser Extension here: https://chromewebstore.google.com/detail/hpedknkjljpopinabjjmljgckhlancni?utm_source=item-share-cb
Leave it on Automatic connection mode unless you are running multiple instances of YetiBrowser MCP Server
Firefox Browser (not currently available)
Due to the limited capabilities of Manifest v3 in Firefox stable release, the Firefox extension is on hold until full support is commonly avaialble (outside of Nightly builds).
MCP Server Installation
Codex CLI
Edit your ~/.codex/config.toml and add the MCP entry:
[mcp_servers.yetibrowser-mcp] command = "npx" args = ["yetibrowser-mcp"]Restart
codex
CLI command; you should seeyetibrowser-mcp
listing under/mcp
tools.If you want to provide a specific port, use this format for the args entry:
args = ["yetibrowser-mcp", "--ws-port", "9010"]
Claude Code
Make sure the extension is installed and connected to a tab, then start the MCP server with
npx yetibrowser-mcp
(or run the locally built CLI).Add the server entry to
~/Library/Application Support/Claude/claude_desktop_config.json
(see the example indocs/publishing.md
).Restart
claude
so it picks up the new MCP server; you should seeyetibrowser-mcp
listed under the/mcp
tools menu once the extension connects.
Other MCP-aware clients
Any MCP client can connect by spawning the CLI (
npx yetibrowser-mcp
) or optionally provide a specific port, e.g.npx yetibrowser-mcp --ws-port 9010
.The server exposes the standard MCP transport over stdio, so use whatever configuration mechanism your client supports to run the command above when a tab is connected.
MCP Inspector
For testing and debugging outside a coding agent.
npx @modelcontextprotocol/inspector yetibrowser-mcp -- --ws-port 9010
to run and inspect the MCP server in conjunction with the YetiBrowser MCP browser extension.
Troubleshooting
The CLI walks ports
9010-9020
until it finds a free one, loggingswitched to
when it advances. Pass--ws-port <port>
if you want to pin a specific port instead.The Browser extension popup mirrors that behaviour: leave it on “Automatic” to track the CLI’s port, or choose “Manual” and enter the port reported by
browser_connection_info
/ the CLI log to override it.Simply ask your AI tool about the connection port. For example:
what is the yetibrowser mcp connction info?
, then set the manual port the port reported.
Documentation & build scripts
Workspace commands live in
docs/workspace-commands.md
.Publishing steps (npm + extension stores) are in
docs/publishing.md
.Screenshot behaviour is documented in
docs/screenshot.md
.Generate distributable Chrome/Firefox zips with
./scripts/package-extensions.sh
(outputs toartifacts/
).A repository-level privacy policy is available in
PRIVACY.md
.
This server cannot be installed
local-only server
The server can only run on the client's local machine because it depends on local resources.
An open-source alternative to BrowserMCP that enables AI assistants to interact with web pages through a Chrome extension. Provides browser automation capabilities without closed-source dependencies by bridging MCP clients to active Chrome tabs.