SSL Expiry Checker
Verify SSL certificate expiry dates and issuer details for any domain instantly
Verify Domain Security
How to check when an SSL certificate expires
Enter a domain name and the tool connects to it, fetches the certificate, and tells you the expiry date, the issuer (CA), and how many days are left. You can check any public-facing domain — your own site, a client's, or a third-party API you depend on.
No software needed. No command line. Just the domain.
Why SSL certificates expire and what happens when they do
Certificate authorities issue SSL/TLS certs with a fixed validity period — currently a maximum of 398 days for publicly trusted certs. When a certificate expires, browsers show a "Your connection is not private" warning and most block the page entirely. Your site doesn't go down, but nobody can reach it without clicking through a scary security warning.
The expiry is intentional — shorter certificate lifespans mean compromised certificates become invalid sooner. Google has been pushing to reduce the max validity to 90 days, which makes automated renewal (like Let's Encrypt with certbot) essentially mandatory.
How to set up automatic SSL renewal
- Let's Encrypt + certbot — free, widely used.
certbot renewin a cron job handles renewal automatically. Renews when 30 days remain. - Cloudflare SSL — if your site is proxied through Cloudflare, they handle the certificate entirely. You don't need to manage it.
- Your hosting provider — most managed hosts (Netlify, Vercel, AWS, etc.) auto-renew certificates. Check your hosting dashboard to confirm.
- acme.sh — lightweight alternative to certbot for servers where you want minimal dependencies
What the certificate details mean
| Field | What it means |
|---|---|
| Common Name (CN) | The domain the cert was issued for |
| Issued By | The Certificate Authority that signed it (Let's Encrypt, DigiCert, etc.) |
| Valid From | When the certificate started being valid |
| Valid Until | When it expires — the date you need to renew before |
| SANs (Subject Alt Names) | Other domains/subdomains covered by the same certificate |
Complete Developer Toolkit
SSL certificate checking is part of a broader domain health and security workflow. Always pair it with our DNS lookup tool — a certificate can be valid but still cause errors if DNS A or CNAME records are pointing to the wrong server. When your SSL certificates are used for API authentication, our JWT decoder inspects the tokens your secured endpoints issue. Our Base64 encoder is useful when working with PEM-encoded certificate data — certificates are Base64-encoded DER files with header/footer lines.
For testing API endpoints that sit behind your SSL certificate, our API response simulator mocks server responses locally. Our URL encoder handles encoding for HTTPS URLs in your API calls. When reviewing security configuration files, our JSON formatter validates JSON-based config formats like Let's Encrypt account files. Our diff checker compares certificate details before and after renewal to confirm the new cert was issued correctly. The Linux terminal cheat sheet covers openssl commands for verifying certificates from the command line alongside this browser tool.