Check a site's SSL certificate: whether it is valid, how many days until it expires, who issued it and which names it covers.
How to use the SSL checker
- Enter a domain.
- Check validity, expiry and covered names.
- Renew or reissue before expiry, and include every hostname you serve.
Why it matters
An expired or mismatched certificate shows visitors a full-page browser warning, and most will leave. Most hosts renew automatically; this confirms they did.
Reading the certificate
Certificate shows Valid when browsers would trust it and it hasn't expired. Expires in turns amber under 30 days and red under 14. Free certificates such as Let's Encrypt last 90 days and usually renew around 30 days before expiry, so a number under 14 means auto-renewal has probably failed. Issuer is the certificate authority. Protocol is the TLS version negotiated; TLSv1.3 or TLSv1.2 is what you want. Covers host says whether the name you entered is on the certificate, directly or through a wildcard such as *.example.com. Error shows why a certificate isn't trusted, and the names list shows every hostname it covers.
Fixing common errors
Expired: renew it, then find out why auto-renewal stopped; often a DNS change or a firewall blocks the validation request. Name mismatch: reissue with every hostname, including both www and the bare domain. Unable to verify or self-signed: the server isn't sending the intermediate certificate; install the full chain from your provider. Wrong certificate entirely: another site on a shared IP is answering, usually a hosting config issue.