Certificate Search

This SSL/TLS certificate search MCP server lets you find, analyze, and enumerate certificates and subdomains by querying crt.sh. It enables you to uncover domain assets, monitor certificate lifecycles, and perform security-focused audits from a unified MCP interface.

How to use

You interact with the Certificate Search MCP Server through an MCP client or compatible tooling. Start by connecting to the MCP endpoint to access the sse stream for live updates and the mcp endpoint for structured commands.

How to install

Prerequisites: Node.js and npm installed on your machine.

1. Clone or download the project into a working directory.

2. Install dependencies.

cd crt-mcp
npm install

3. Run in development mode to test locally.

npm run dev

4. Deploy to Cloudflare Workers.

npm run deploy

Additional setup and access

After deployment, the MCP server is accessible at the following endpoints.

MCP live stream and control endpoints:

• sse: https://crt-mcp.<your-account>.workers.dev/sse

• mcp: https://crt-mcp.<your-account>.workers.dev/mcp

REST API endpoints

In addition to the MCP protocol, you can access a REST API for certificate search and details.

Search certificates by domain across records

GET https://crt-mcp.<your-account>.workers.dev/api/certificates/search?domain=example.com&matchType=wildcard&limit=10

POST https://crt-mcp.<your-account>.workers.dev/api/certificates/search
  -H "Content-Type: application/json"
  -d '{"domain":"example.com","matchType":"wildcard","limit":10}'

Get details for a specific certificate using its ID.

GET https://crt-mcp.<your-account>.workers.dev/api/certificates/details?certId=123456789

Connecting tools and clients

You can connect with Cloudflare AI Playground or Claude Desktop to experiment with the MCP server.

Cloudflare AI Playground setup steps are available by entering your MCP URL in the playground.

To use with Claude Desktop, configure the mcp-remote proxy in your settings to point to the deployed MCP URL.

{
  "mcpServers": {
    "certificate-search": {
      "command": "npx",
      "args": [
        "mcp-remote",
        "https://crt-mcp.<your-account>.workers.dev/sse"
      ]
    }
  }
}

Security and usage notes

Use this MCP server to discover domain assets, monitor certificate expirations, enumerate subdomains, and perform SSL/TLS audits in a controlled environment.

Available tools

search_certificates

Searches for SSL/TLS certificates by domain with options for exact, wildcard, or subdomain matching and a configurable limit.

get_certificate_details

Retrieves full details for a specific certificate using its certificate ID.

analyze_certificates

Analyzes certificate usage for a given domain to understand distribution, issuing authorities, and expiry status.

get_help

Provides service help and usage guidance for end users.