Quickstart

From zero to a working scrape in five minutes.

Quickstart

Get a browser engine, start the MCP server, and drive webrain from an LLM — in five minutes.

1. Install webrain

Linux / macOS

curl -fsSL https://raw.githubusercontent.com/prokopis3/webrain/main/scripts/install.sh | bash

2. Get a browser engine

webrain install   # downloads Chrome for Testing (first time only)

This downloads Chrome for Testing into a cache dir; that build then wins discovery over your system Chrome. See Installation for other engines (--engine obscura) and OS specifics.

3. Start the MCP server

webrain mcp             # stdio transport (VS Code / Copilot / Claude)
webrain mcp --http 9223 # HTTP transport on 127.0.0.1:9223

Logs go to stderr; MCP speaks pure JSON on stdout — never redirect stderr into the stream.

4. Connect an LLM client (MCP setup)

Webrain is an MCP server - register it in your client and the 51 webrain_* tools appear automatically. Two transports:

• stdio - webrain mcp (default; simplest for local clients)
• HTTP - webrain mcp --http 9223, endpoint http://127.0.0.1:9223/mcp

{
  "mcp": {
    "servers": {
      "webrain": {
        "type": "stdio",
        "command": "webrain",
        "args": ["mcp"],
        "env": { "CDP_URL": "http://127.0.0.1:9222" }
      }
    }
  }
}

Or over HTTP (start webrain mcp --http 9223 first):

{
  "mcp": {
    "servers": {
      "webrain": { "type": "http", "url": "http://127.0.0.1:9223/mcp" }
    }
  }
}

Claude Desktop - claude_desktop_config.json:

{
  "mcpServers": {
    "webrain": { "command": "webrain", "args": ["mcp"] }
  }
}

Cursor - project .mcp.json:

{
  "mcpServers": {
    "webrain": { "command": "webrain", "args": ["mcp"] }
  }
}

Restart the client, then verify the server is live: ask the LLM to call webrain_guide - it returns the browser/challenge/extraction decision guide.

Then ask the LLM something like:

Scrape all product titles + prices from URL X

The model calls webrain_navigate → webrain_autoschema → webrain_extract_json and returns structured data. No selectors on your part.

Drive it by hand instead?

Every engine + tool has a CLI twin:

webrain doctor                # full diagnosis: engines, MCP, CDP, vault, sidecar
webrain fetch https://example.com
webrain screenshot https://example.com
webrain eval "document.title"
webrain launch scrapingcourse demo "https://example.com/login" --port 9222