SSL Checker — Free Online SSL Certificate Status Tool
Check any domain's SSL certificate validity, expiry date, issuer, SANs, and TLS protocol version in real time.
Jump to tool ↓Frequently Asked Questions
SSL/TLS Certificate Validation
SSL/TLS certificates are the foundation of HTTPS security. They authenticate your server identity and encrypt traffic between the server and browser. An expired, misconfigured, or untrusted certificate immediately breaks HTTPS and displays browser security warnings to all visitors.
This SSL checker performs a live TLS handshake with the target server and extracts the certificate details: expiry date, issuer chain, subject alternative names, serial number, fingerprint, and TLS protocol/cipher information. This is the same information a browser inspects when establishing a secure connection.
Regular SSL monitoring is essential for production infrastructure. Certificate expiry is a common cause of outages — even experienced teams let certificates lapse. Set up automated monitoring alerts at 60, 30, and 14 days before expiry to avoid service disruptions.
Standards & References
Built and maintained by DevDecode. This live network check sends the domain you enter to our server; DNS lookups also query Google's DNS service. Found an issue? Let us know.
Related Tools
Related Guides
How to Fix Slow DNS Lookups: 6 Proven Fixes
Slow DNS lookups delay every website you visit. Learn how to fix slow DNS — switch to a faster resolver, flush the cache, rule out VPN/antivirus interference, and diagnose the problem with dig and nslookup.
CertificatesWhat Happens When an SSL Certificate Expires (and How to Check)
When an SSL certificate expires, browsers block the site with a security warning. Learn the exact impact, how to check a certificate's expiration date, and how to prevent downtime.
CertificatesWhat Is an SSL/TLS Handshake? Step-by-Step
The TLS handshake negotiates encryption before any data flows. Here's each step — ClientHello to Finished — plus how TLS 1.3 cut it to one round trip.
Certificates'Fix "unable to get local issuer certificate"'
'The "unable to get local issuer certificate" error means a missing intermediate or untrusted root. Here is what causes it and how to fix it in curl, Node, Python, Git, and Java.'