CertAvert monitors SSL/TLS certificates on any port and alerts you before users notice. Free for 15 domains. It catches expiring, expired and revoked certificates, incomplete chains, hostname mismatches, self-signed or untrusted certificates and old TLS versions, and flags unexpected certificate changes. Alerts by email, plus Slack and Discord on paid plans. Free tools, no sign-up: SSL/TLS, SANs, chain, TLS and DNS checks and a certificate/CSR decoder. Pro adds an inventory and audit report.

Hi everyone, I'm the maker of CertAvert. 👋

I built it after seeing too many sites go down for something as simple as an expired certificate. Since launch, it's grown a lot:

• Free tools, no sign-up: SSL/TLS, SANs, chain, TLS and DNS checks, plus a certificate/CSR decoder. Try one on your own domain at certavert.com

• Alerts for revoked certificates and unexpected certificate changes, not just expiry

• Checks the certificate on every IP a domain resolves to

• Email, Slack, Teams and Discord alerts

• Pro: inventory and an audit-ready certificate report

With certificate lifetimes dropping to 100 days in 2027 and 47 days by 2029, renewals will happen a lot more often, and a missed one will be easier to make.

Free for 15 domains. I'd love your feedback: what would make it more useful for you?