Subdomain API is a remote MCP server that gives an AI agent 2 tools, among them count_subdomains, find_subdomains. It answers at https://api.subdomain.app/mcp over streamable HTTP, and it listed its tools to an anonymous client, so no sign-in was needed for that. Our probes reached it 10 of 10 times since 4 September 2026; the last check, on 17 October 2026, succeeded.
Find known subdomains of a domain. Passive data; may include historic entries. List or count.
Description as the publisher wrote it.
| Tool | What it does |
|---|---|
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 Inputs: domain |
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 Inputs: domain, limit |
Every block below points at https://api.subdomain.app/mcp. Pick your client and copy.
claude mcp add --transport http subdomain-api https://api.subdomain.app/mcp
{
"mcpServers": {
"subdomain-api": {
"command": "npx",
"args": ["-y", "mcp-remote", "https://api.subdomain.app/mcp"]
}
}
}{
"mcpServers": {
"subdomain-api": {
"url": "https://api.subdomain.app/mcp"
}
}
}{
"servers": {
"subdomain-api": {
"type": "http",
"url": "https://api.subdomain.app/mcp"
}
}
}{
"context_servers": {
"subdomain-api": {
"url": "https://api.subdomain.app/mcp"
}
}
}{
"mcpServers": {
"subdomain-api": {
"serverUrl": "https://api.subdomain.app/mcp"
}
}
}{
"mcpServers": {
"subdomain-api": {
"url": "https://api.subdomain.app/mcp"
}
}
}name: Subdomain API
version: 0.0.1
schema: v1
mcpServers:
- name: Subdomain API
type: streamable-http
url: https://api.subdomain.app/mcp{
"mcpServers": {
"subdomain-api": {
"httpUrl": "https://api.subdomain.app/mcp"
}
}
}{
"mcpServers": {
"subdomain-api": {
"type": "http",
"url": "https://api.subdomain.app/mcp"
}
}
}{
"mcpServers": {
"subdomain-api": {
"url": "https://api.subdomain.app/mcp"
}
}
}goose://extension?url=https%3A%2F%2Fapi.subdomain.app%2Fmcp&type=streamable_http&id=subdomain-api&name=Subdomain%20API
It answered our last check on 17 October 2026 in 231 ms. Over 10 checks since 4 September 2026 it answered 10. Status here comes from Neuronto's own probes, not from the publisher.
Yes. It is published by subdomain.app and served from api.subdomain.app, the vendor's own domain: https://api.subdomain.app/mcp.
2, as returned by the server's own tools/list on 9 September 2026: count_subdomains, find_subdomains.
It answered our last check on 17 October 2026 in 231 ms. Over 10 checks since 4 September 2026 it answered 10.
Put the server under mcpServers in ~/.cursor/mcp.json with the URL https://api.subdomain.app/mcp. The exact JSON is above, with the same setup for Claude Code, Claude Desktop, VS Code, Windsurf, Zed, Gemini CLI and the rest.
It listed its tools to an anonymous client, so reading the tool list needs no key. Individual tools can still ask for credentials in their own inputs.
Publisher: app.subdomain. Endpoint host: api.subdomain.app. ARD identifier: urn:air:app.subdomain:mcp:subdomains.
First indexed 31 August 2026. The tools are exactly what the server returned; nothing on this page
is inferred from its name. Ranking in Neuronto search is never for sale.