Anyone who inherited a server deserves an answer they can forward.

Paste a hostname. Certscan opens a real TLS connection, reads the certificate the server actually presents, and tells you in plain language: when it expires, who issued it, every hostname it covers, and whether the chain the server sent is complete.

Note: A host behind Cloudflare cannot be reached from this check. Use the live check on any other host.

The chain, not just the date

Most certificate checkers stop at the expiry date. Expiry matters, but the failure that actually costs a weekend is the one nobody looks for: a server that sends only the leaf certificate without its intermediate. Desktop browsers paper over it from cache. Mobile clients refuse to load the page. That problem is invisible to anyone checking only the date.

Expiry — the obvious one

How many days until the certificate expires, or when it already has. One sentence, no arithmetic.

Chain completeness

How many certificates the server actually sent. A leaf alone is a red flag. A full chain with intermediates is green.

Issuer and subjects

Who issued the certificate, and every hostname it covers — Subject Alternative Names listed plainly, not buried in a hex dump.

Raw details when you need them

Serial number, fingerprint, validity window, and every certificate in the chain, available for inspection.

How it works

Paste a hostname

Just the hostname — no scheme, no path. A plain address like github.com.

Certscan opens a real TLS connection

A server-side TLS handshake reads the certificate chain the way a browser would. There is no cache, no proxy, no local store — the answer is always live.

Read the verdict

Expiry date, days remaining, issuer, SANs, chain length. A sentence you can forward to whoever owns the server.

That is all

No account, no alerts, no scheduled re-checks. This tool answers when you ask it and forgets immediately. Your hostname is never stored.

What a report looks like

A verdict rendered as a lead sentence, with quiet fields beneath it — a lab report you can hand to whoever fixes the server.

The certificate on demo.example.com expires in 12 days, on 2026-09-10.
Status Chain complete — 3 certificates sent
Issuer R3 (Let's Encrypt)
Subject demo.example.com
SANs demo.example.com, www.demo.example.com
Days remaining 12
The certificate on broken.example.com expires in 44 days, on 2026-10-13. The chain the server sent is incomplete.
Status Incomplete chain — only leaf certificate sent
Days remaining 44