Subdomain API

Find known subdomains of a domain.

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What it can do

    What data it sees

    Do you need an account

    No: the server works without sign-in

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

    Server tool list (2)

    Raw names from tools/list. Only developers need these.

    find_subdomainsList 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`.
    count_subdomainsReturn 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.
    Subdomain API: connect to Claude, ChatGPT, Cursor · Connectors.fun