Crtsh MCP server

@pipeworx/crtsh

Certificate Transparency log search from crt.sh — every TLS certificate ever issued for a domain and its subdomains, with issuer, validity window, serial number and the full SAN list.

Part of Pipeworx — an MCP gateway connecting AI agents to 1679+ live data sources.

Tools

every logged certificate for a domain, de-duplicated by certificate id and sorted newest-first, plus unique_names: every distinct hostname seen across all of them. That list is the subdomain-enumeration answer most callers actually want.

• crtshsearchdomain(domain, includesubdomains?, excludeexpired?, limit?) —

or by hex serial number. Returns the PEM body; a lookup by serial also carries the logged metadata, a lookup by id returns the PEM alone (see Traps).

• crtshcertificate(id?, serial?, includepem?) — one certificate by crt.sh id

Auth

Keyless.

Data sources

identity (domain, SAN, or %-wildcard).

• — certificate search by

• — certificate search by hex serial.
• > — the PEM body of one certificate.

crt.sh is operated by Sectigo and is a JSON view over a PostgreSQL database of the public Certificate Transparency logs.

Traps

and the server enforces no query timeout of its own. Every call in this pack is bound at 25s rather than the pack default.

• crt.sh is slow. A wildcard query on a large domain routinely takes 10-20s

serial=, Identity=. ?id=&output=json answers the literal string Unsupported output type: json with HTTP 200. Parsed without checking, that is a silent zero; crtJson() rejects any body that does not start with [ or {.

• output=json is honoured only for identity-style queries — q=,

id renders an HTML page. This is why crtsh_certificate can return the PEM for an id but not its metadata — there is no JSON-by-id endpoint, so metadata arrives only on the serial= path.

• ?d= and ?id= are different parameters. d returns the PEM;

it is the difference between reporting 8 certificates and the 40 hostnames the caller asked for.

• namevalue packs every SAN into one newline-separated field.** Splitting

(certificate, matching identity), so a cert with six matching SANs is six rows with the same id. De-duplicate by id or every count is inflated.

• One certificate appears as several rows — crt.sh returns one row per

crt.sh ids and the same serial number, so an id count roughly doubles the number of certificates actually issued. crtshsearchdomain reports both: totallogentriesfound (distinct crt.sh ids) and uniquecertificates_found (distinct serials). Quote the second one when answering "how many certificates".

• A precertificate and its final certificate are two CT entries with two

CA appears nowhere here; an empty result is not proof the host does not exist.

• CT covers publicly trusted CAs only. A host behind an internal or private

Quick Start

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

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

What this endpoint actually serves

tools/list at https://gateway.pipeworx.io/crtsh/mcp returns the tools in the table above plus the shared Pipeworx meta-tools — askpipeworx, discovertools, 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.

Shortened. The full README is on GitHub.