SSL Certificate Checker
Paste a URL and see whether the certificate is valid, whether the chain is complete, and exactly how many days are left before it expires. Free, no signup.
What the SSL check reports
● EXPIRY
Days until it expires
The exact expiry date and a days-remaining countdown — the number that turns a quiet renewal failure into something you can act on.
● VALIDITY
Is the certificate trusted?
Confirms the certificate is currently valid and actually covers the hostname you asked about — not a mismatched or already-expired one.
● CHAIN
Complete chain to a trusted root
Catches the missing intermediate that your own browser hides from you because it cached it from another site — but a client's fresh browser will not.
● HTTPS ENFORCEMENT
HTTP → HTTPS redirect
A valid certificate is not much use if plain HTTP visitors never reach it. We confirm the redirect works, and flag redirect loops.
Every run is a full sweep, so you also get uptime, broken links, redirects, HTTP status codes, domain expiry, SEO metadata and DNS —see the full website checker.
Why certificates lapse even with auto-renewal
The ACME challenge broke.Let's Encrypt has to prove you still control the domain. Move a DNS record, change a web root, or add a redirect in front of /.well-known/and the renewal starts failing — silently, until the old certificate runs out.
The timer stopped.A server rebuild, a migrated container, or a disabled cron job takes the renewal with it. Nothing errors, because nothing runs.
The CDN is serving the old one.The origin renewed correctly, but the certificate visitors actually see is the stale one held at the edge. Checking the origin tells you nothing here — you have to check what a visitor gets.
A check tells you today. Monitoring tells you 30 days out.
This is a one-time snapshot. If you manage client sites, SitesRadar's paid plans run this check on a schedule across your whole roster and alert you well before a certificate lapses.
Guides on SSL failures
Frequently asked questions
- What is an SSL certificate checker?
- It is a tool that connects to a site over HTTPS and reports whether its TLS certificate is valid, whether the chain back to a trusted root is complete, who issued it, and how many days remain before it expires. Paste a URL and you get the answer without running an
opensslcommand. - How do I check when an SSL certificate expires?
- Paste the site's URL into the checker above. The report shows the exact expiry date and the number of days remaining. In a browser you can also click the padlock and view the certificate, but that only tells you about the site you happen to be visiting, one at a time.
- Why does my certificate work in one browser but not another?
- Almost always an incomplete chain. The server sends the leaf certificate but omits the intermediate, and browsers that happen to have cached that intermediate from another site still trust it while a fresh client does not. Our checker validates the chain from a clean state, so it catches the case your own browser hides from you.
- Does a valid certificate mean HTTPS is set up correctly?
- Not by itself. A site can hold a perfectly valid certificate and still serve plain HTTP to anyone who types the bare domain. That is why this check also confirms HTTP visitors are redirected to HTTPS, and flags redirect loops in the process.
- My certificate auto-renews. Do I still need to check it?
- Yes. Auto-renewal fails quietly more often than people expect — a moved DNS record breaks the ACME challenge, a cron timer stops firing after a server rebuild, or a CDN keeps serving the old certificate after the origin renewed. The renewal is automated; noticing that it stopped is not.
- Can I monitor SSL expiry instead of checking manually?
- That is what SitesRadar's paid plans do — they run this check on a schedule across every site you manage and alert you days before a certificate lapses, rather than relying on you to remember to check.