Subdomain API
Find known subdomains of a domain. Passive data; may include historic entries. List or count.
Connect it
Settings → Connectors → Add custom connector
URL: https://api.subdomain.app/mcpSettings → Apps & Connectors → Advanced → Developer mode
Create connector with URL: https://api.subdomain.app/mcp{
"mcpServers": {
"subdomains": {
"url": "https://api.subdomain.app/mcp"
}
}
}claude mcp add --transport http subdomains https://api.subdomain.app/mcp{
"servers": {
"subdomains": {
"type": "http",
"url": "https://api.subdomain.app/mcp"
}
}
}2 tools, verified live
find_subdomainsread-onlyList 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 â re-query rather than caching the result. Use for attack-surface mapping, security recon, asset inventory, o
count_subdomainsread-onlyReturn only the total number of distinct subdomains known for a domain â 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.
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