Subdomain API Documentation
Find the subdomains of a domain name.
Query endpoint
GET https://api.subdomain.app/v1/query?domain=example.com
Query parameters:
domain: the root domain to look up (e.g.example.com). Enter the registrable domain;www., scheme, and path are stripped.
Returns up to 10,000 subdomains,
most recently seen first. No pagination. count is the
number returned; total is the distinct number of
subdomains known for the domain.
Response:
{
"domain": "example.com",
"count": 2,
"total": 2,
"subdomains": [
"www.example.com",
"mail.example.com"
]
}
Limits
- Fair-use rate limiting applies. Too many requests in a short time may be rate-limited (HTTP 429); slow down and retry.
- Maximum 10,000 subdomains per response.
Errors
400: invalid or missingdomain.429: rate limit exceeded.503: temporarily unavailable.
OpenAPI
Machine-readable specification: openapi.json.
MCP server
Prefer to use this from an AI agent? The same data is available over the
Model Context Protocol at https://api.subdomain.app/mcp. See
the MCP docs for client configs
(Claude, Cursor, VS Code, Gemini, Codex, ChatGPT, and more).
