Subdomain API

app.subdomain/subdomains

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

healthy

status

tools exposed

866ms

connect latency

3364641bb18f

schema fingerprint

Tools (2)

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

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 change

Endpoint

https://api.subdomain.app/mcp
Category: Other · Last checked: 2026-07-30T12:47:51Z

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How we measure →

What this means. This server responded to the MCP handshake and listed its tools without authentication. The schema fingerprint lets us flag if tool signatures silently change (schema drift) between checks.