SSL / HTTPS Checker
Check any domain's SSL certificate — validity dates, issuer, SANs, and days until expiry.
Valid From / Valid To
The date range during which the certificate is trusted by browsers. Outside these dates the site will show a security warning to visitors. Most certificates are issued for 90 days (Let's Encrypt) or 1–2 years (paid CAs).
Days Left
Green (60+ days) — all good, no action needed.
Yellow (30–59 days) — plan your renewal soon.
Red (<30 days) — renew immediately or visitors will see SSL errors.
Issuer
The Certificate Authority (CA) that signed and vouches for this certificate. Common issuers include Let's Encrypt (free, auto-renews), Sectigo, DigiCert, and Comodo (paid, longer validity).
SANs (Subject Alt Names)
The list of domains and subdomains this certificate covers. A wildcard entry like *.example.com covers all subdomains. If your domain isn't listed here, browsers will show a warning.
Certificate Chain
SSL trust works as a chain — your cert is signed by an intermediate CA, which is trusted by a root CA built into browsers. A broken chain (missing intermediate) causes SSL errors even with a valid cert.
Signature Algorithm
The cryptographic algorithm used to sign the certificate. SHA-256 (or stronger) is the current standard and fully trusted. Older algorithms like SHA-1 are deprecated and flagged by browsers.