SSL tools Certificate decoder
Paste an SSL certificate and read its domain, issuer and expiry date — with nothing to install.
An issued SSL certificate is readable text once decoded — this tool does that for you and shows everything clearly: which domain it's valid for, who issued it, and until when. The text should start with -----BEGIN CERTIFICATE----- and end with -----END CERTIFICATE-----. If the certificate is in DER or PFX format, convert it to PEM with the SSL converter first.
Also need to check whether the certificate matches a private key? See certificate/key matcher, or check the installation with the SSL checker.