SSL Certificate Check
Connect to a host on port 443 (or any port) and inspect the TLS certificate it presents, including how many days remain before it expires.
- Runs on our servers
- Free, no sign-up
About this tool
A TLS certificate proves that a server is who it claims to be and enables the encrypted connection behind every https:// address. Certificates expire, get revoked and are sometimes issued for the wrong names, and when that happens visitors see a full-page browser warning. The SSL Certificate Check connects to the host you specify, retrieves the leaf certificate and reports everything you need to judge it: validity window, issuer, subject alternative names, key strength, signature algorithm and fingerprints.
Use it to confirm a renewal went live, to verify that a wildcard covers a new subdomain, or to audit third parties before integrating with them. Data comes from the APIVoid SSL Info API, which also checks revocation status and the SSLBL abuse list.
What this tool gives you
Validity at a glance
Valid, expired, revoked, self-signed, name mismatch and days-left verdicts with colour-coded badges.
Subject and issuer
Who the certificate was issued to, by which certificate authority, and the validation type (DV, OV or EV).
Technical details
Key algorithm and size, signature algorithm, serial number, SHA-1 and SHA-256 fingerprints and CRL endpoints.
Frequently asked questions
Does the check follow redirects?
No. It opens a TLS connection directly to the hostname and port you enter and reports the certificate that server presents during the handshake.
Why does it say name mismatch?
The hostname you entered is not listed in the certificate common name or subject alternative names. Browsers show a warning in exactly this situation.
Can I check a mail or custom port?
Yes, change the port field: 465 or 993 for mail servers, 8443 for admin panels, or any other port that speaks TLS directly.
How early should I renew?
Most certificate authorities now issue 90-day certificates. Renew at least two weeks before the expiry date and automate it wherever possible.