SSL & Security

Check SSL Expiration Date

Expiry Dates

Check SSL certificate expiration

Enter a domain name and port to check the SSL certificate expiration date and status.
Alert me at

Reads the leaf certificate's notBefore/notAfter dates, the issuing chain and the SAN list straight from the TLS handshake. The window you pick decides when the result is flagged as expiring, and how early the .ics reminder fires.

Tool features

Comprehensive SSL certificate expiration checking with detailed status information
4 checks

Expiration Date Check

Get accurate SSL certificate expiration dates and remaining validity period

Certificate Status

Verify SSL certificate validity with detailed status information and warnings

Port Support

Check SSL certificates on custom ports (default 443) for comprehensive testing

Real-time Validation

Instant SSL certificate validation with detailed issuer and validity information

What is SSL certificate expiration & how it works

Validity windows, renewal timing, and avoiding outages

Every SSL/TLS certificate has a fixed validity window with a hard expiry date. The moment it passes, browsers stop trusting the site and show a full-page security warning — even if nothing else about the server changed. Because publicly-trusted certificates are now capped at short lifetimes (about 13 months), expiry is one of the most common and most avoidable causes of website outages.

This checker connects to the domain, reads the certificate the server presents, and reports exactly when it was issued and when it expires — plus how many days remain. Use it to catch certificates that are close to lapsing, confirm an automated renewal actually deployed, and keep a simple calendar of expiry dates across your domains.

Validity period
The notBefore–notAfter window during which a certificate is trusted. Publicly-trusted certs are now limited to roughly 13 months.
Days remaining
How long until expiry. A common alerting threshold is 30 days — enough lead time to renew and deploy safely.
Auto-renewal
ACME clients like Certbot renew certificates automatically. Always verify the new cert actually installed on the server.

How to use this tool

Check a certificate's expiry date in four steps
1
Enter a domain and port
Type the hostname and port (443 for HTTPS, or a custom port for other TLS services).
2
Run the expiry check
We read the live certificate and calculate the exact expiry date and days remaining.
3
Review the expiry status
See when the certificate expires and whether it is inside a safe renewal window.
4
Renew before it lapses
Renew and redeploy well before the expiry date — ideally at least 30 days out.

Related tools

Keep debugging with tools from the same suite
3 tools
SSL Checker
Comprehensive SSL certificate analysis including validity, expiration, chain verification, TLS versions, and security assessment
Certificate Decoder
Decode and analyze SSL certificate contents, properties, and metadata in detail
SSL Scanner
Advanced SSL/TLS security scanner with comprehensive vulnerability assessment and configuration analysis

Frequently asked questions

Common questions about SSL certificate expiry
5 Q&A

Publicly-trusted TLS certificates are currently capped at about 398 days (roughly 13 months). Internal or private-CA certificates can be longer, but browsers reject public certs that exceed the limit.

Renew at least 30 days before expiry. That leaves time to deploy, test, and recover if the renewal or installation fails.

Browsers show a full-page 'Your connection is not private' warning and block the site until it is renewed. HTTPS traffic effectively stops working.

Yes. Auto-renewal can silently fail if the ACME challenge breaks, a service isn't reloaded, or the new cert isn't installed on every server. Monitoring the live expiry date catches those gaps.

It can. Different services on different ports may present different certificates, so check the specific port your users connect to.