# checker-mcp

A local-first MCP server for auditing domain security and privacy. It runs 17 live checks without telemetry and produces a score from 0 to 100.

- MCP server · `type=mcp` · Claude Code, Codex, Cursor, GitHub Copilot, Windsurf (Devin Desktop), Cline, Zed, Gemini CLI
- Author: OksigeniaSL
- License: GPL-3.0 · policy=link-only · description only; the file stays with the author
- Source: https://github.com/OksigeniaSL/checker-mcp
- Updated: 2026-07-22
- HTML: https://affpapa.org/en/nevibecode/mcp/checker-mcp

## What it does

The server operates entirely over stdio on your machine. Network calls hit only the target domain over HTTPS, Cloudflare DoH rather than Google resolvers, the HSTS preload registry, and `rdap.org` for registration records. It keeps your activity private by bypassing third-party scoring services.

Seventeen checks cover four areas: SSL certificates, mail verification (SPF, DKIM, DMARC, MTA-STS, BIMI), DNS records, and HTTP security headers. Each failed test comes with a concrete fix step. You can fetch output either as a formatted report or raw JSON.

Clients interact with three exposed tools: `check_domain`, `list_checks`, and `explain_check`. Node.js with `npx` is required to run the package directly, though a Docker container is also an option. If firewalls block outbound traffic to Cloudflare DoH or RDAP endpoints, domain reputation scans will fail.

## Requirements
- Needs: Node.js (commands run via npx)

## Install

### Claude Code (native platform)

**Platform CLI**
```bash
claude mcp add checker-mcp -- npx -y @oksigenia/checker-mcp
```

### Codex

**Platform CLI**
```bash
codex mcp add checker-mcp -- npx -y @oksigenia/checker-mcp
```

### Cursor

**Config file**
File `.cursor/mcp.json`:
```json
{
    "mcpServers": {
        "checker-mcp": {
            "command": "npx",
            "args": [
                "-y",
                "@oksigenia/checker-mcp"
            ]
        }
    }
}
```

### GitHub Copilot

**Config file**
File `.vscode/mcp.json`:
```json
{
    "servers": {
        "checker-mcp": {
            "type": "stdio",
            "command": "npx",
            "args": [
                "-y",
                "@oksigenia/checker-mcp"
            ]
        }
    }
}
```

### Gemini CLI

**Platform CLI**
```bash
gemini mcp add checker-mcp npx -y @oksigenia/checker-mcp
```

## When to use it
- Inspect SSL certificate validity and expiration dates
- Audit email authentication records including SPF, DKIM, and DMARC
- Evaluate HTTP security headers such as CSP and HSTS
- Check domain status against known malware and phishing lists

## Example prompts
- Check the security posture of example.com and show the report
- Explain the dmarc check and provide steps to fix issues
- List all available security checks with their explanations

## Similar
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- [Porkbun DNS 🐷](https://affpapa.org/en/nevibecode/mcp/porkbun-dns.md) — MCP server · ★ 23
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- [ToolPipe MCP Server](https://affpapa.org/en/nevibecode/mcp/ithiel-labs-toolpipe-mcp-server.md) — MCP server · ★ 7
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