SSL Certificate Checker

What this SSL certificate checker does

This tool is a TLS certificate checker for public hostnames. Compathub resolves your name to public IPv4 or IPv6 addresses, connects to port 443 on one validated address, and inspects the certificate the server presents during the TLS handshake. Use it to check SSL certificate expiry, confirm the issuer, read Subject Alternative Names (SANs), and see whether verification and hostname matching succeed.

Certificate verification and hostname checks stay enabled on the server side. A failed verification is never reported as a valid certificate. You also see validity dates, days remaining, negotiated TLS version, and chain details when the handshake exposes them.

When to use it

• Before launch or migration: confirm the live hostname serves the certificate you expect.
• Renewal planning: spot certificates expiring within 30 days (shown as expiring soon).
• Debugging HTTPS: compare hostname mismatch, untrusted chain or connection errors with plain-language next steps.

Limitations

• Only port 443 is checked. Other TLS ports, client certificates and mTLS are not supported.
• Results reflect one connection from Compathub servers, not every browser or corporate trust store.
• OCSP stapling, Certificate Transparency logs and internal CA deployments may need separate tooling.
• This is not a full penetration test or automated vulnerability scan.

Related Compathub tools

Start with DNS Lookup to confirm A and AAAA records for the hostname. After HTTPS works, use the Security Headers Checker for HSTS and CSP on the same site, the Redirect Checker to follow HTTP to HTTPS chains, the Website Response Time Checker for a server-side latency snapshot on the live URL, and Reverse IP Lookup if you need PTR names for the resolved addresses. For CMS or CDN clues, try the Website Stack Checker.

Browse every tool on the Compathub homepage or read the FAQ for accuracy and privacy notes.