SSL Certificate Checker

Read the HTTPS certificate: issuer, SANs, and days left.

Host

Calculated Result

Enter a target and run

Formula: TLS :443 → peer certificate dates & SANs

Next steps

About this calculator

We open a TLS session to port 443 with SNI. The peer certificate is parsed even if the chain fails verification, so you can still inspect dates.

FormulaTLS handshake → peer certificate validity window

tls.connect → getPeerCertificate(true) → valid_from / valid_to / fingerprint.

Check if a domain looks free via public RDAP.

Age from the RDAP registration date.

Preview favicons and the Open Graph image.

Redirect chain and response headers.