mcpbeat

Subdomain API MCP Server

app.subdomain/subdomains
answering

Subdomain API is answering right now. Last checked 3 min ago. It exposes 2 tools.

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

Uptime history 41 hours of history
41 hours agonow
100.0%
Uptime 24h
91 of 91 checks
2
Tools
read from the server
357 ms
Response time
average over 24h
open, no key
Access
streamable-http

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 3 min ago.

run in your terminal
claude mcp add subdomains --transport http https://api.subdomain.app/mcp
~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "subdomains": {
      "url": "https://api.subdomain.app/mcp"
    }
  }
}
~/.codex/config.toml
[mcp_servers.subdomains]
url = "https://api.subdomain.app/mcp"
.cursor/mcp.json
{
  "mcpServers": {
    "subdomains": {
      "url": "https://api.subdomain.app/mcp"
    }
  }
}
.vscode/mcp.json
{
  "mcpServers": {
    "subdomains": {
      "url": "https://api.subdomain.app/mcp"
    }
  }
}

Available tools 2

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

count
count_subdomains
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 changes over time, so treat it as current-as-of-query, not a fixed value.
subdomains
find_subdomains
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 rather than caching the result. Use for attack-surface mapping, security recon, asset inventory, or SEO host discovery. Hostnames are returned most-recently-seen first. The response always reports `total` (full distinct count known) and a `truncated` flag, so you can tell when more exist beyond `limit`.

Endpoints

URLTransportStateLatencyChecked
https://api.subdomain.app/mcp streamable-http answering 445 ms 3 min ago

Subdomain API — questions

Answers built from our own checks of this server.

What can Subdomain API do?
It exposes 2 tools, read directly from the server on our last check. Among them: count_subdomains, find_subdomains. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →
Is Subdomain API working right now?
We send a real MCP handshake every 15 minutes. Over the last 24 hours 91 of 91 checks got a reply (100.0%), average response time 357 ms. The bar chart above shows every period we have measured.
How do I connect Subdomain API?
Copy the ready config from this page — we generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each with the file path that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.
Does Subdomain API need an API key?
No. Subdomain API completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 2 of them are readable on this page. This is what we observed, not what the docs claim.
How fast is Subdomain API?
It answers our handshake in 357 ms on average, which is faster than 39% of all working MCP servers we measure. The comparison comes from our own checks across the whole registry, every 15 minutes.