MCP server

Subdomain API Official

app.subdomain/subdomains

Checked 26 Oct 2026, 08:29 UTC · Connected to it and listed its tools

Find known subdomains of a domain. Passive data; may include historic entries. List or count.

Website

At a glance

Type

MCP server

Publisher

subdomain.app (verified by the MCP Registry)

Status

Working at last check

Tools

2

Token cost

About 530 tokens per request

Sets up in

Claude Code, Claude Desktop, Codex, Gemini CLI, Cursor, VS Code, Antigravity, ChatGPT, OpenAI API, Grok

Last checked

26 Oct 2026, 08:29 UTC

Connect it to your agent

Add to CursorAdd to VS CodeVS Code Insiders

Opens the app, which shows the server and asks you to confirm. For other apps, copy the setup below.

Claude Code

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

Claude Desktop

Settings → Connectors → Add custom connector, and paste the URL.

Codex (config.toml)

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

Gemini CLI

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

Cursor

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

VS Code

{"servers":{"subdomains":{"type":"http","url":"https://api.subdomain.app/mcp"}}}

Antigravity

agy mcp add subdomains https://api.subdomain.app/mcp

ChatGPT

Settings → Apps & Connectors → Advanced settings: turn on Developer mode, then Create a connector and paste the URL. Which plans can do this varies.

OpenAI API (Responses tools)

{"type":"mcp","server_label":"subdomains","server_url":"https://api.subdomain.app/mcp","require_approval":"always"}

Grok (xAI API tools)

{"type":"mcp","server_label":"subdomains","server_url":"https://api.subdomain.app/mcp"}

Tools

• count_subdomains ~204 tokens
  Return only the total number of distinct subdomains known for a domain — no list. Cheap and low-token. Use when the user asks "how many subdomains" or you only need the size of the attack surface. Count includes historic subdomains that may no longer be live. It is a point-in-time figure that change
• find_subdomains ~326 tokens
  List known subdomains (hostnames) of a root domain. Data is passive (not active scanning): results are historic observations and may include subdomains that no longer resolve or are no longer live. Results are a point-in-time snapshot that changes over time as new subdomains are observed — re-query

Browse

• SEO
• Website monitoring

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