Yab, Yet Another Browser

What Yab, Yet Another Browser does

Yab, Yet Another Browser gives an MCP client access to a real Yab browser on a Mac. The browser uses the user's existing sign-ins, cookies, saved-password filling, and network identity while keeping passwords hidden from the agent. Agent-created tabs are placed beside the user's tabs in Yab and can remain out of view until requested.

The server is intended for local browser automation that requires authenticated sites. It can also connect a remote assistant to Yab through the preview remote-assistant flow, with the person approving the connection in Yab.

How it works

The package locates the Yab application, preferring the YAB_APP path when set, then checking the yab command and common application locations before using Spotlight. It starts Yab's MCP command with YAB_CLI=1 and passes the MCP client's standard input, output, signals, and exit status through to the app.

If Yab is unavailable or the command runs away from a Mac, the package uses a built-in fallback that exposes a tool snapshot and explains how to obtain Yab. The package itself does not make network requests. With Yab closed, the first request can open it without a visible window; yab serve keeps it running in that mode.

Yab, Yet Another Browser supports a remote mode for assistants on another computer. Run npx yab-mcp login --client dots --nonce NONCE, approve the displayed eight-character code in Yab, and then use npx yab-mcp --remote or the task and status commands. The remote connection token is stored in ~/.config/yab-mcp/auth.json unless YAB_MCP_AUTH_FILE changes the location.

Setup and configuration

Use macOS 15.4 or later, install Yab, and enable agent access under Yab's Settings > AI > Agents. Node.js 18 or later is needed for the npx setup. Claude Code, Codex, Cursor, VS Code, Windsurf, Claude Desktop, and other stdio MCP clients can launch npx -y yab-mcp.

Without Node.js, configure the client to run /Applications/yab.app/Contents/MacOS/yab mcp with YAB_CLI=1. Yab's developer settings can add the server to Claude Code or Codex and can copy configuration for other clients. The optional YAB_MCP_URL selects a test remote service; production uses the documented sync endpoint.

Tools and capabilities

Yab, Yet Another Browser exposes tools for:

• Listing, opening, navigating, and grouping browser tabs and spaces.
• Reading pages as accessibility trees and interacting through clicks, typing, choices, key presses, hovering, dragging, dialogs, and scrolling.
• Reading selected Developer Tools data, including console messages, network metadata, styles, comments, and performance traces.
• Inspecting and applying supported native Yab actions, checking operation status, and undoing eligible native changes.

The running Yab version determines the final tool list, so newer app versions may expose more tools than the included snapshot.

Limitations and notes

This server requires a Mac for normal browser operation and depends on the installed Yab app and its agent permission. Sensitive actions such as Send, Pay, and Delete wait for approval in Yab unless the user enables Bypass. Saved passwords are filled by Yab and are not exposed to the agent.

Chrome is not required. Users who want existing Chrome sign-ins in Yab can use yab import chrome, after approving the import in Yab. The remote-assistant feature is marked as a 0.2.0 preview and requires a person to authorize the connection on the Mac.