Certificate Expiration Checker
Parse a PEM-encoded X.509 certificate and check its validity period, expiration date and remaining time.
What is Certificate Expiration Checker?
Check when a PEM-encoded X.509 certificate expires. Paste a certificate to inspect its validity period, calculate the remaining time and determine whether the certificate is currently valid, expired or not yet valid.
How to use
- Paste a PEM-encoded X.509 certificate.
- Parse the certificate and read its validity period.
- Check the certificate start and expiration dates.
- Review the remaining validity time.
- Check the current certificate status.
Features
- PEM certificate parsing
- Expiration date detection
- Certificate start date detection
- Remaining validity calculation
- Expired certificate detection
- Not-yet-valid certificate detection
- Current validity status
- Browser-side processing
Common Use Cases
- Checking TLS certificate expiration
- Monitoring certificate validity
- Debugging HTTPS configuration
- Checking certificates before deployment
- Certificate development and testing
Example
-----BEGIN CERTIFICATE----- MIIB...certificate data... -----END CERTIFICATE-----
Valid from: 2026-01-01 Valid until: 2027-01-01 Status: Valid Remaining validity: 87 days
FAQ
What does Certificate Expiration Checker do?
It reads the validity period of an X.509 certificate and shows whether the certificate is currently valid, expired or not yet valid.
Can I check a TLS certificate?
Yes. You can paste the PEM representation of an X.509 TLS certificate and check its expiration date and validity status.
Can the tool tell me how many days are left?
Yes. The checker calculates the remaining validity based on the certificate expiration date and the current date.
Does the checker verify whether a certificate is trusted?
No. It checks the certificate's validity dates but does not determine whether the certificate is trusted by a browser, operating system or certificate authority.
Can it detect an already expired certificate?
Yes. The tool compares the certificate validity period with the current date and reports an expired status when appropriate.
Missing a feature?
If this tool doesn't cover your use case or is missing functionality, please let me know through the Contact page.
New improvements and features are added based on user feedback.