Commoncrawl MCP Server

@pipeworx/commoncrawl

Common Crawl's public web archive — find every time a URL was crawled since 2008 and read back the exact page bytes that were captured.

Part of Pipeworx — an MCP gateway connecting AI agents to 1688+ live data sources. This is an independent, unofficial integration — not affiliated with, endorsed by, or published by the upstream provider.

Tools

• commoncrawl_crawls(limit?, contains_date?) — the monthly crawl collections (CC-MAIN-2026-34 and friends) with the capture window each one covers. contains_date answers "which snapshot would have seen my page on that day".
• commoncrawl_index_search(url, crawl?, match_type?, limit?, page?, filter?, from?, to?) — CDX index lookup for a URL, host or whole domain. Returns capture timestamp, HTTP status, MIME type, detected language, content digest, and the WARC filename + offset + length that the next tool needs.
• commoncrawl_fetch_record(filename, offset, length, max_body_bytes?) — reads one archived record back by byte range: WARC headers, the captured HTTP response headers, and the page body as crawled.

Auth

Keyless.

Data sources

• https://index.commoncrawl.org/collinfo.json — the crawl collection list.
• https://index.commoncrawl.org/{crawl}-index — the CDX index, JSON-lines.
• <https://data.commoncrawl.org/{warc path}> — WARC records, HTTP range reads.

Things the next person would otherwise rediscover

• The CDX host 502s sporadically under load. Measured 2026-09-17: the same url=example.com query alternated between 200 and nginx 502 inside a minute, so it is load, not the query. ccFetch retries a 5xx twice with a short backoff. Without that a caller reads transient nginx noise as "Common Crawl has no record of this URL", which is a different and wrong answer.
• "No captures" is a 404 with an English sentence, not JSON. Handled as an empty result set with an explicit note, so an empty captures array is never silently indistinguishable from an upstream failure.
• Each indexed record is its own gzip member, so a byte-range read of offset..offset+length-1 decompresses standalone — no need to stream the whole 1 GB WARC. DecompressionStream('gzip') handles it in the Workers runtime.
• new TextDecoder('utf-8', { fatal: false }) does not typecheck against @cloudflare/workers-types: its TextDecoderConstructorOptions requires ignoreBOM too. Pass no options; non-fatal is the default anyway.
• A broad match_type: "domain" query over a large domain is expensive upstream and is the first thing to 502. Narrow with match_type: "host" plus a filter such as =status:200.

Related packs

crawlgraph is our own link graph over sites we crawl. This pack reads the Common Crawl Foundation's corpus — different data, different questions.

Quick Start

Add to your MCP client (Claude Desktop, Cursor, Windsurf, etc.):

{
  "mcpServers": {
    "commoncrawl": {
      "url": "https://gateway.pipeworx.io/commoncrawl/mcp"
    }
  }
}

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/commoncrawl/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — ask_pipeworx, discover_tools, search_within, remember/recall and the rest of the gateway-wide set. So the tool count you see is larger than this table: a single-pack endpoint currently lists roughly 30 shared tools alongside the pack's own. The connection's initialize response states its exact scope, and is the authoritative answer for a given day.

This is deliberate, not multiplexing by accident. The meta-tools are what let a scoped connection answer a question this pack does not cover — via ask_pipeworx, which routes across the whole catalog — without you adding a second MCP server. There is currently no way to mount a pack endpoint without them; if the extra schemas cost you more context than the routing is worth, connect to the full gateway once rather than to several pack endpoints.

Or connect to the full Pipeworx gateway to get every pack's tools listed directly, instead of just this one's:

{
  "mcpServers": {
    "pipeworx": {
      "url": "https://gateway.pipeworx.io/mcp"
    }
  }
}

Both URLs reach the same gateway and the same 1688+ data sources. The only difference is which pack's tools are listed directly; ask_pipeworx reaches all of them from either one.

No MCP client? Call it over HTTP

curl -X POST https://gateway.pipeworx.io/v1/tools/commoncrawl_crawls \
  -H 'Content-Type: application/json' \
  -d '{"limit":3}'

No account needed for the first calls. Inspect any tool: GET https://gateway.pipeworx.io/v1/tools/commoncrawl_crawls. Find one: POST https://gateway.pipeworx.io/v1/tools/search_packs with {"query":"..."}.

Standalone (no gateway account)

This package also runs as a local stdio MCP server — no Pipeworx account, no gateway round-trip:

{
  "mcpServers": {
    "commoncrawl": {
      "command": "npx",
      "args": ["-y", "@pipeworx/mcp-commoncrawl"]
    }
  }
}

Or run it directly to confirm it starts:

npx -y @pipeworx/mcp-commoncrawl

It speaks MCP over stdin/stdout and answers initialize/tools/list/tools/call for only this pack's tools — none of the shared meta-tools the gateway connection above adds. Same source, same tools, no ask_pipeworx routing.

Using with ask_pipeworx

Instead of calling tools directly, you can ask questions in plain English — this works on the pack endpoint above as well as on the full gateway:

ask_pipeworx({ question: "your question about Commoncrawl data" })

The gateway picks the right tool and fills the arguments automatically.

More

• Docs and guides
• pipeworx.io

License

MIT