SSL Certificate Checker
Check a website's SSL/TLS certificate — issuer, validity dates and days remaining until expiry.
About this tool
This tool inspects a website's SSL/TLS certificate — the file a server presents to prove its identity and enable encrypted HTTPS connections — and reports its subject, issuer, validity window and any subject alternative names (additional hostnames the same certificate covers).
How to use this tool
- Enter a domain name, e.g.
example.com. - Select "Check certificate".
Frequently asked questions
Why does this tool need an external service?
Cloudflare Workers — the platform this site runs on — terminate TLS internally and do not expose the raw certificate of a third-party site to application code. Reading real certificate details for an arbitrary host requires either a dedicated certificate-inspection service or a raw TLS client, so this tool uses a pluggable provider interface rather than fabricating results.
What counts as "expiring soon"?
This tool flags certificates with fewer than 30 days remaining before expiry as a warning, since renewal can sometimes take time to propagate, particularly with manual certificate management.
Does a valid certificate mean a site is completely safe?
No. A valid, unexpired certificate confirms the connection is encrypted and the certificate matches the domain — it says nothing about the trustworthiness of the site's content.
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