SSL Expiry Monitor
Check a site's certificate validity and expiry date
SSL Expiry Monitor — Complete Guide & Instructions
MakeCard SSL Expiry Monitor connects to any public hostname on port 443 and reads its live TLS certificate — the subject it is issued to, the issuing CA, valid-from and expiry dates, days remaining, and every alternate domain (SAN) the certificate covers. A color-coded badge flags certificates that are expired, expiring within 15 days, or healthy. Built for site owners, sysadmins, and anyone verifying HTTPS setup.
How to Use SSL Expiry Monitor
- 1 Enter a hostname such as example.com in the Hostname field.
- 2 Click "Check Certificate" — the tool opens a TLS connection to that host.
- 3 Read the expiry badge: green for healthy, amber for under 15 days left, red for expired.
- 4 Review the details — Issued to, Issuer, Valid from, Expires on, and the covered domain list.
Key Features & Capabilities
- Live TLS handshake against the real server — not cached data.
- Days-left badge color-coded: expired, under 15 days, or valid.
- Full certificate identity — subject, issuer, validity window.
- Subject Alternative Name list showing every covered domain.
- Accepts hostnames with or without https:// and port suffixes.
- Instant result with host:port confirmation.
Supported Formats & Specifications
| Parameter | Specification |
|---|---|
| Check Type | Live TLS connection to hostname:443 |
| Output Fields | Subject, issuer, valid from, valid to, days left, SANs |
| Alert Bands | Expired (red), <15 days (amber), valid (green) |
| Input | Hostname only — scheme and port are stripped automatically |
| Method | Server-side certificate read (browsers cannot open raw TLS) |
Practical Everyday Use Cases
- Verifying a renewed certificate actually deployed on the live server.
- Checking days remaining before a certificate expires.
- Confirming which domains a SAN or wildcard certificate covers.
- Auditing a vendor or client site's HTTPS configuration.
- Troubleshooting a browser "certificate expired" warning.
Pro Tips for Best Results
- Renew before the amber zone — under 15 days leaves little room for CA delays.
- Check every subdomain separately; each host presents its own certificate.
- Match the SAN list against all the domains your site serves to catch coverage gaps.
- If expiry looks wrong, confirm you are hitting the real host and not a CDN alias.
Common Problems & Solutions
The host may block non-HTTPS probes, use a non-443 port, or sit behind a firewall — verify the hostname resolves and serves TLS on 443.
You are likely seeing the CDN or shared-hosting certificate — check the SAN list for your domain among the covered names.
Browsers may have cached or the site serves a fallback chain — trust the live read; renew immediately.
Privacy & Security
100% Client-Side Execution
The hostname you enter is sent to our server, which opens a TLS connection to read the public certificate — the standard way browsers cannot do directly. We do not log or store the hostnames you check.
Frequently Asked Questions
Everything you need to know about using SSL Expiry Monitor
Enter the domain in this tool — it connects to the site, reads the live certificate, and shows the exact expiry date plus how many days remain.
Browsers display a full-page security warning and most visitors will leave. APIs and payment gateways may refuse connections entirely, so renew before expiry.
Subject Alternative Names list every domain the certificate covers — e.g. example.com, www.example.com, api.example.com on one cert. The tool shows the full SAN list.
Sites behind Cloudflare or similar CDNs present the CDN's edge certificate. Your origin server may have a separate certificate — check the SAN list for your domain.
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