SSL Certificate Monitoring Made Simple — Node.js One-Liner

SSL certificate expiry is one of the most common causes of website outages. Here's how to check it in Node.js: import https from " https " ; const req = https . request ({ hostname : " google.com " , port : 443 , method : " HEAD " }, res => { const cert = res . socket . getPeerCertificate (); const validTo = new Date ( cert . valid_to ); const daysLeft = Math . floor (( validTo - new Date ()) / 86400000 ); console . log ( `Issuer: ${ cert . issuer . O } ` ); console . log ( `Expires: ${ cert . valid_to } ` ); console . log ( `Days left: ${ daysLeft } ` ); console . log ( `Status: ${ daysLeft < 30 ? " WARNING " : " OK " } ` ); }); req . end (); What You Get Issuer (Google Trust Services, Let's Encrypt, etc.) Expiry date with days remaining Subject Alt Names (which domains the cert covers) Protocol version (TLS 1.2, 1.3) Fingerprint for verification At Scale I built an SSL Certificate Checker that processes multiple domains and flags: Expired certificates Certificates expiring within 30