Tools / Subdomain Finder (Certificate Transparency) + Live Check

Subdomain Finder (Certificate Transparency) + Live Check

Find subdomains of any domain passively from public Certificate Transparency logs (crt.sh, with CertSpotter fallback). Input: domains. Output (JSON/CSV): one row per item with domain, subdomain, firstSeen, lastCertExpiry, issuer, resolves, ips, cname, httpStatus, pageTitle.

Run it on Apify Store →

What it's for

Attack-surface / asset inventory for your own domains
Alert when a new subdomain (new product, staging site) appears
Competitive intel: spot new product launches from new certificates

Example input

{
 "domains": [
  "apify.com",
  "therealtour360.com"
 ],
 "resolveDns": true,
 "probeHttp": true,
 "maxSubdomainsPerDomain": 40,
 "monitorMode": true
}

Example output

{
  "domain": "apify.com",
  "subdomain": "staging.apify.com",
  "firstSeen": "2026-02-09T00:00:00Z",
  "lastCertExpiry": "2027-03-10T23:59:59Z",
  "issuer": "Amazon Trust Services",
  "certCount": 10,
  "wildcard": true,
  "certCurrentlyValid": true,
  "isNew": null,
  "resolves": false,
  "cname": null,
  "ips": [],
  "dnsStatus": "NOERROR"
}

Input reference

Field	Type	Notes
`domains` required	array	Root domains, e.g. example.com.
`resolveDns`	boolean	Look up A/CNAME for each subdomain (via public DNS-over-HTTPS).
`probeHttp`	boolean	Request https:// of live subdomains for status code and title.
`includeExpired`	boolean	Include subdomains with only expired certificates
`maxSubdomainsPerDomain`	integer	Max subdomains per domain
`monitorMode`	boolean	Remember subdomains; later runs flag new ones.
`onlyNew`	boolean	In monitor mode, output only new subdomains.
`stateStoreName`	string	State store name

Pricing

Pay per event: Subdomain row $0.0005. Plus Apify's small per-run start fee. Apify's free plan includes monthly credit to try it.

How to run

Open the Store page and click Try for free.
Fill in the input (or paste the example JSON in the JSON tab).
Click Start, then export results as CSV, Excel or JSON, or call it via the Apify API.
Optional: add a Schedule and a webhook/Slack/email integration for ongoing monitoring.

Open Subdomain Finder (Certificate Transparency) + Live Check on Apify →