About CertPost

Why CertPost exists

Most certificate monitoring checks whether a renewal job ran. CertPost checks what your server actually serves to a real visitor: the certificate on the wire, the full chain, the hostname, the fingerprint. A renewal log can say success while your visitors see an expired or mismatched certificate. Most certificate outages live in that gap.

CertPost does one job well. It watches your certificates and sends one alert you can act on, at 30, 14, 7 and 1 days, to a human who can fix it. There are no uptime probes and no dashboard to babysit.

A note from the founder

I lost three launch days on a previous product, Hypersend, to SSL certificates. I had one certificate from my registrar, one left over from an old host, and Vercel trying to issue a third. Some visitors got the wrong certificate, some got a security warning, and every fix looked done until a cached DNS answer somewhere proved it wasn't. Nothing showed up in any log I owned.

CertPost is the page I needed that week. It checks the certificate your visitors actually receive, from the outside, and tells a human before it breaks. I point it at everything I run.

— Mark Musson, founder

Who we are

CertPost is built and operated by Kryptoplus Labs Ltd, a software company registered in London (EC2A), United Kingdom.

Questions, feedback, or a certificate story we should hear? Email support@certpost.ai. We reply within one business day.

What we do with your data

We store the endpoints you ask us to monitor and the certificate metadata we observe on them, and nothing else. We never see your traffic, your keys, or your content, and we never sell or share monitoring data. Checks connect from the outside, exactly like a browser would.