Subdomain MCP server

Look up subdomains from your AI agent as a native tool.

Endpoint

The same subdomain data is available over the Model Context Protocol (Streamable HTTP) at https://api.subdomain.app/mcp. No key, no signup. Two tools: find_subdomains and count_subdomains.

Add it to your client

Claude Code

claude mcp add --transport http subdomain-app https://api.subdomain.app/mcp

Cursor, Windsurf, Claude Desktop (MCP config)

{
  "mcpServers": {
    "subdomain-app": { "url": "https://api.subdomain.app/mcp" }
  }
}

VS Code (GitHub Copilot)

code --add-mcp '{"name":"subdomain-app","type":"http","url":"https://api.subdomain.app/mcp"}'

Gemini CLI (~/.gemini/settings.json)

{
  "mcpServers": {
    "subdomain-app": { "httpUrl": "https://api.subdomain.app/mcp" }
  }
}

Codex (~/.codex/config.toml)

[mcp_servers.subdomain-app]
url = "https://api.subdomain.app/mcp"

Antigravity (~/.gemini/antigravity/mcp_config.json)

{
  "mcpServers": {
    "subdomain-app": { "serverUrl": "https://api.subdomain.app/mcp" }
  }
}

ChatGPT

Turn on Developer mode (Settings → Apps & Connectors → Advanced), create a connector, and paste https://api.subdomain.app/mcp as a Streamable HTTP endpoint with no authentication. Requires a paid plan (Plus, Pro, Team, Enterprise, or Edu).

Tools

find_subdomains — list known subdomains of a domain (with an optional limit).
count_subdomains — return only the total count.

Registry

Published to the official MCP Registry as app.subdomain/subdomains. Machine-readable metadata: server.json. Prefer the JSON API instead? See the API docs.

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