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SSL Checker

Check SSL/TLS certificate details for any domain via public certificate APIs. View issuer, validity period, days remaining, and SANs. Expiry alerts catch outages before users do — free, no signup. Uses cloud-based processing.

Cloud AI Browser Native

How to Use the SSL Checker

1. Enter the domain

Any hostname — certificate fetched via public certificate APIs, with a transparency-log fallback.

2. Read validity and issuer

Issuer, validity window, days remaining and SANs.

3. Renew before expiry

Under 30 days means renew now; re-check after install.

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Frequently Asked Questions

What SSL certificate details does it show?

Certificate issuer (e.g., Let's Encrypt, DigiCert), validity period (not-before and not-after dates), days remaining until expiration, serial number, and Subject Alternative Names (SANs).

Can I check if a certificate is about to expire?

Yes. The tool shows the exact expiration date and calculates days remaining. Use this to monitor your own domains or verify a site's certificate is current.

Does it check the full certificate chain?

It shows chain entries when the certificate API returns them. The transparency-log fallback carries no live chain — confirm expiry against the live server before acting.

What is a SAN (Subject Alternative Name)?

A SAN is an additional domain name or IP address covered by the same certificate. Many certificates secure multiple domains (e.g., example.com and www.example.com) via SANs.

Is the check query stored?

No. Your browser queries third-party certificate APIs (ssl-checker.io with a crt.sh fallback), so the checked domain is visible to those providers. No search history is stored on our server.

When does a certificate count as expiring?

Fewer than 30 days remaining reads Expiring, below 0 reads Expired. Each provider gets 15 seconds before the fallback runs, and the recent-checks row keeps your last 5 domains.

Related Developer Tools

SSL/TLS Checker

Check a host over HTTPS from your browser — SSL/TLS reachability (which proves the browser validated the certificate chain) plus public issuance history (issuer, expiry, cert count) via crt.sh. No cipher-suite or protocol-version scan: browsers do not expose handshakes.

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Decode and view SSL certificate details including subject, issuer, and validity period. Code never leaves your device — formatting and validation run locally in your browser.

Last updated October 2026