Yab, Yet Another Browser MCP server

yab-mcp

The MCP server of Yab, Yet Another Browser, for Claude Code, Codex, Cursor and any MCP client.

Yab, Yet Another Browser, is a free WebKit browser for the Mac. With this server, any agent gets one real browser on your Mac: the one you're signed in to. Your agent opens tabs of its own beside yours, reads pages as text, clicks, types and fills forms with your sign-ins, your cookies and your IP. There is no cloud browser, no debug port and no Chrome to set up, and it's free. A press on Send, Pay, Delete and the like waits for your yes on a card in Yab, unless you chose Bypass in Yab's settings: the browser holds that yes, not the model. Saved passwords are filled by Yab and never shown to the agent. Agent tabs live in a window off screen and come in front of you only when you ask. With Yab closed, the first call opens it hidden, with no window and no Dock tile, and it quits after half an hour with nothing to do. yab serve keeps it running that way.

Download Yab · For developers · Manual

Remote assistants (0.2.0 preview)

On the assistant's own computer, run npx yab-mcp login --client dots --nonce NONCE. It prints the code and returns immediately; a background process saves the connection after the person allows it in Yab. Yab on the Mac shows the eight-character code under Settings > AI > Assistants. After the person allows it there, use npx yab-mcp --remote as a stdio MCP server, or npx yab-mcp task "Find a table for Friday" to give Yab one task. The task command prints its session ID and returns; a shell-only assistant can run npx yab-mcp status SESSION to wait for the next update, or omit SESSION to check its newest task after a Mac reconnects. Repeat until it says done. The connection token stays in ~/.config/yab-mcp/auth.json (mode 0600), or the path in YABMCPAUTHFILE. YABMCP_URL selects a test server; production uses https://yab-sync.21st.workers.dev. Without --remote, this package still uses the local Yab app exactly as before.

Requirements

• A Mac with macOS 15.4 or later.
• Yab, free: download. It updates itself.
• Agents allowed in Yab: Settings › AI › Agents › Let agents use Yab. Until then, every call says so.
• Node.js 18 or later, for npx. A client can also run Yab directly, without Node: see Without Node.

Chrome is your main browser? Yab can still be the one your agents use, usually closed. yab import chrome brings Chrome's sign-ins into Yab after you say yes in Yab, so your agent hits fewer sign-in pages.

Already use Yab? Settings › Developers adds it to Claude Code and Codex with one click, and Copy Config gives the JSON for any other client. You don't need this package for that.

Install

Claude Code

The plugin brings the tools and Yab's skill:

/plugin marketplace add yetanotherbrowser/yab-mcp
/plugin install yab@yab-mcp

From a shell: claude plugin marketplace add yetanotherbrowser/yab-mcp, then claude plugin install yab@yab-mcp.

Only the tools:

claude mcp add --scope user yab-browser -- npx -y yab-mcp

If Yab's Settings › Developers already added Yab to Claude Code, skip this: you'd have the same tools twice.

Codex

The plugin, tools and skill:

codex plugin marketplace add yetanotherbrowser/yab-mcp
codex plugin add yab@yab-mcp

Or only the tools, in ~/.codex/config.toml:

[mcp_servers.yab-browser]
command = "npx"
args = ["-y", "yab-mcp"]
tool_timeout_sec = 900
default_tools_approval_mode = "approve"

tooltimeoutsec lets a call wait up to 15 minutes while Yab asks you something; the plugin keeps Codex's default of 5. defaulttoolsapproval_mode stops Codex asking before every Yab tool; Yab still asks you before Send, Pay and Delete. Leave it out if you want Codex to ask too.

Cursor

Shortened. The full README is on GitHub.