certindex-mcp

An MCP (Model Context Protocol) server

that exposes CertIndex's Certificate

Transparency search tools to any MCP-compatible client (Claude

Desktop, the MCP Inspector, Continue, etc.).

CertIndex indexes the full public CT corpus (~5 M certificates, growing

~100 k/day). This server wraps the public CertIndex REST API so an LLM

can ask questions like:

• "List every TLS certificate ever issued for `example.com`."
• "What subdomains has Let's Encrypt seen for `mycompany.io`?"
• "Show me certs expiring in the next 30 days for `api.mycompany.io`."
• "Pull the full PEM and CT log metadata for SHA-256 ``."

Why this repo exists

The CertIndex monorepo bundles an MCP server (mounted at

`https://api.ctindex.io/mcp`) that talks directly to the production

Postgres index. This standalone package is a thin client-side

shim: it speaks MCP to your editor / agent and forwards every tool

call to the hosted CertIndex REST API over HTTPS. Two consequences:

1. You don't need a copy of the index — sign up for a free API key

at https://ctindex.io and you're done.

2. The package has a tiny dependency footprint (`mcp`, `httpx`,

`pydantic`) — easy to audit, easy to vendor, no DB drivers.

Install

pip install certindex-mcp

Or with `uvx` for one-shot use:

uvx certindex-mcp

To install the latest development version from source instead:

pip install git+https://github.com/certindex/certindex-mcp

Quickstart — Claude Desktop

Add to `~/Library/Application Support/Claude/claude_desktop_config.json`

(macOS) or `%APPDATA%\Claude\claude_desktop_config.json` (Windows):

{
  "mcpServers": {
    "certindex": {
      "command": "uvx",
      "args": ["certindex-mcp"],
      "env": {
        "CERTINDEX_API_KEY": "ctx_live_..."
      }
    }
  }
}

Restart Claude Desktop. The ten CertIndex tools appear in the tool tray.

Tools

Ten tools, matching the hosted CertIndex MCP server 1:1:

Quickstart — MCP Inspector

export CERTINDEX_API_KEY=ctx_live_...
npx @modelcontextprotocol/inspector uvx certindex-mcp

Configuration

Security

Input validation, rate-limit handling, and our supply-chain posture are

documented in SECURITY.md. Please report vulnerabilities

to security@ctindex.io rather than filing public issues.

Development

git clone https://github.com/certindex/certindex-mcp
cd certindex-mcp
pip install -e ".[dev]"
pytest

CI runs on Python 3.11 / 3.12 / 3.13.

License

MIT © CertIndex contributors.