Crab MCP Server
Let Claude, Cursor, VS Code, Codex and Gemini crawl your site and read the audit.
By Abhinav Vasudevan · Published Oct 3, 2026
Crab is a free SEO crawler that runs on your computer. Since version 1.6 it also works as an SEO MCP server. MCP is the standard way AI assistants use outside tools. Connect it once, and your assistant can start crawls, read the technical SEO audit and tell you exactly which page to edit, without exporting a single CSV.
Download Crab, freemacOS, Windows and Linux · no account · no URL limits
What you can ask
“Crawl example.com and list every broken link, grouped by the page I need to edit.”
Starts a crawl, waits for it, then returns each broken URL with the pages and anchor text that link to it.
“What got worse since last week's crawl?”
Compares the two latest crawls of the site: new issues, fixed issues and pages that changed status.
“Show the audit summary for my site.”
Health score, page breakdown and the top issues, each with how to fix it and example URLs.
“Export every page with a missing meta description.”
Writes the full list to a file and gives a summary by folder, so a 10,000-page site never floods the chat.
“Recrawl my site every Monday at 9am.”
Sets a recurring crawl on the project.
On a big site, large results are written to a file in ~/.crab/exports and the assistant gets a summary (affected pages by folder and status code, and the pages linking to the most broken URLs) so a 10,000-page site never floods the conversation.
Set it up in a minute
- Download Crab. On Mac, drag it into Applications (Crab offers to do this if you open it from the disk image).
- In Crab, click Connect AI in the status bar. It shows the exact command or config for your assistant, with the right path for your machine.
- Restart your assistant if it asks, then ask it to crawl a site.
For reference, these are the setups on a Mac with Crab in Applications:
Claude Code
Run once in a terminal.
claude mcp add --scope user crab -- /Applications/Crab.app/Contents/MacOS/Crab mcpClaude Desktop
Easiest: download the .mcpb extension from the latest release and double-click it. Or open Settings → Developer → Edit Config, add this, and restart Claude.
{
"mcpServers": {
"crab": {
"command": "/Applications/Crab.app/Contents/MacOS/Crab",
"args": ["mcp"]
}
}
}Codex
Run once in a terminal. The Codex CLI, IDE extension and the ChatGPT desktop app's Codex tab share it.
codex mcp add crab -- /Applications/Crab.app/Contents/MacOS/Crab mcpGemini CLI
Run once in a terminal.
gemini mcp add -s user crab /Applications/Crab.app/Contents/MacOS/Crab mcpCursor
Add to ~/.cursor/mcp.json, or Cursor Settings → MCP → Add new server.
{
"mcpServers": {
"crab": {
"command": "/Applications/Crab.app/Contents/MacOS/Crab",
"args": ["mcp"]
}
}
}VS Code
Add to .vscode/mcp.json, or run “MCP: Add Server” from the command palette.
{
"servers": {
"crab": {
"type": "stdio",
"command": "/Applications/Crab.app/Contents/MacOS/Crab",
"args": ["mcp"]
}
}
}18 tools for technical SEO
| Tool | What it does |
|---|---|
| start_crawl | Crawl a site (scope, depth, JavaScript rendering, user agent, URL exclusions) |
| wait_for_crawl | Wait for a running crawl to finish |
| get_crawl_status | Progress of a running crawl |
| stop_crawl | Stop a running crawl |
| preflight_url | Check a URL's redirects before crawling |
| list_projects | Every crawl you've run |
| list_crawl_history | Earlier crawls of the same site |
| get_audit_summary | Health score, page breakdown and top issues with fixes |
| list_issues | Every issue the audit found |
| get_issue_pages | The pages behind one issue, with the pages linking to them |
| export_issue | Full list of pages for an issue, saved to a file with a summary |
| query_pages | Filter pages by status, type, title, word count and more |
| export_pages | Save any page list to a file |
| get_page | Everything about one URL: tags, headings, links, schema |
| get_links | Inlinks and outlinks of a page, with anchor text |
| get_external_links | Every outbound link on the site |
| compare_crawls | What changed between two crawls |
| set_schedule | Recurring crawls |
Crab also ships four ready-made prompts your assistant can start from: a full technical audit, fixing broken links, what's changed since the last crawl, and a pre-launch check.
Which MCP server is best for SEO?
It depends on the data you need. MCP servers for SEO come in two kinds, and they work well together:
- Crawlers look at your own site: broken links, redirects, titles, canonicals, schema, sitemaps. Crab and Screaming Frog are in this group.
- SEO data tools look at the web around it: backlinks, keyword volumes, rankings, competitor traffic. Ahrefs is in this group.
| Data | Runs | Cost | |
|---|---|---|---|
| Crab | Technical crawl and audit | On your computer | Free |
| Screaming Frog MCP | Technical crawl and audit | On your computer (SEO Spider 24+) | Paid licence |
| Ahrefs MCP | Backlinks, keywords, traffic | Ahrefs' servers | Lite plan or higher, uses API units |
If you want your assistant to audit and fix your own site, start with a crawler. Add a backlink and keyword tool when you need data about other sites. See also Crab vs Screaming Frog.
Frequently Asked Questions
Yes. Crab and its MCP server are free, with no URL limits, no account and no API key.
Questions? hey@crab.so or r/crabdotso