Subdomain Takeover Checker

Checks common subdomain names for a "dangling" CNAME: one pointing at a third-party platform (GitHub Pages, S3, Heroku, Netlify, Vercel and about a dozen more) whose resource there was since deleted. Those can often be silently re-claimed by anyone on that platform, letting them serve their own content and often piggyback on your cookies, CSP and SPF trust from your own subdomain. A clean result means no obvious risk was found among the names checked, not a certified-clear attestation.

📖 Guide: What subdomain takeover is

Last updated: August 29, 2026