SSL Certificate Checker
SSL certificate checker — expiry, hostname match, trust chain, SANs, and certificate transparency hostnames.
About this tool
Connect to a public HTTPS endpoint on port 443 and inspect the TLS certificate the server presents. Spot renewal deadlines, name mismatches, incomplete chains, and weak settings before browsers or API clients reject the site.
What you get
- Pass/fail verdict with plain-language issues (expiry, trust, hostname, weak crypto)
- Whether the certificate matches the hostname (CN, SAN, wildcard)
- Not-before and not-after dates, issuer, public key, and negotiated TLS version
- Full SAN list, intermediate chain table, and CT log hostnames when available
How to use
Enter the hostname only (no https:// path). Only check hosts you are allowed to probe.
Sample TLS certificate summary
A healthy public site certificate often reports:
| Field | Value |
|---|---|
| Subject | CN=www.example.com |
| Issuer | Let's Encrypt R3 |
| Valid until | 2026-06-15 (62 days remaining) |
| SANs | example.com, www.example.com |
| Trust | Trusted chain, hostname match OK |
Weak ciphers, expiry warnings, and CT log hostnames appear in the full check.
Glossary
- SAN
- Subject Alternative Name — additional hostnames covered by one certificate.
- Chain of trust
- Intermediate certificates linking the leaf cert to a trusted root CA.
- CT logs
- Certificate Transparency logs listing certificates issued for a domain.
FAQ
How to check SSL certificate expiry online?
Enter a hostname to connect over HTTPS and read not-before and not-after dates plus days remaining before renewal is due.
How to run a free SSL test online?
Enter any public hostname — the SSL test connects on port 443 and reports certificate expiry, chain trust, hostname match, and TLS details without signup.
How to test if an SSL certificate is valid and trusted?
The verdict covers chain completeness, trust anchor validation, hostname match, and weak cipher or protocol issues in plain language.
How to see all hostnames on an SSL certificate?
SAN names from the leaf certificate are listed, plus certificate transparency hostnames discovered for the domain.
What does an SSL checker show besides expiry?
Pass/fail summary, certificate and chain tables, protocol details, cipher info, and actionable issues such as name mismatch or incomplete chain.
How to find certificate transparency logs for a site?
The report lists publicly logged hostnames—useful for discovering forgotten subdomains and mis-issued certificates.
Why does my site show certificate errors in the browser?
Common causes are expired cert, wrong hostname in SAN, incomplete intermediate chain, or untrusted issuer—the checker flags each with a readable explanation.
By using this tool you agree to our Terms of Use and Privacy Policy. Results are provided as-is without warranty.