SSL Checker

SSL Checker connects to a domain over TLS and reads the live certificate to confirm it is valid, correctly chained and not about to expire. Whether you’re auditing your own site or a client’s, this page explains the ssl checker tool concept end-to-end and, gives you a free, working free ssl checker tool below.

How it works

Enter a domain. We open a TLS socket connection on port 443, retrieve the peer certificate, and parse it to report the issuer, subject, validity window and days remaining until expiry.

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What we check

• Certificate issuer and subject (including SANs)
• Valid-from and valid-to dates
• Days remaining until expiry
• Self-signed or otherwise untrusted certificates
• Protocol/port reachability

How to fix common SSL Checker issues

1. Renew certificates before the expiry window (most CAs support auto-renewal — enable it).
2. Make sure the certificate covers both the root domain and the www subdomain.
3. Remove mixed-content (HTTP) resources on HTTPS pages.
4. Redirect all HTTP traffic to HTTPS with a 301.

FAQs