SSL Checker

The SSL Checker inspects any website's SSL/TLS certificate in seconds — showing whether it's valid and trusted, when it expires, which domains it covers, who issued it, and whether the server's encryption is still safe. Catch a missing chain, an expiring certificate, or a domain mismatch before your visitors hit a security warning. Free, with no signup.

See Your Encryption as a Visitor Does

The checker opens a real secure connection to the domain you enter and reads the certificate the server actually presents — not how it looks from inside your own network. That outside perspective matters, because the most damaging SSL problems are invisible from your own browser. In one run, it reports certificate validity, expiry, chain completeness, covered domains, issuer, and the TLS version and ciphers negotiated.

How to Use It

1. Enter a domain like example.com.
2. Check the certificate — a live connection retrieves it.
3. Review the results and fix anything flagged.

The #1 Hidden Bug: A Missing Intermediate

This is the classic "works on my machine" SSL failure. A server should send its leaf certificate plus every intermediate up to a trusted root. When an intermediate is missing, your own browser often fills the gap from its cache and the site looks fine — but a fresh client with no cache (a mobile app, a payment gateway, an API, a search crawler) rejects the connection outright. The checker validates the chain exactly as a first-time visitor would, exposing the broken link you'd otherwise never see. The fix: install the complete chain on the server.

A Valid Certificate Isn't the Same as a Secure Server

Here's a distinction many tools blur. A certificate proves identity and enables encryption — but a server with a flawless certificate can still negotiate obsolete protocols (TLS 1.0/1.1), weak ciphers, or sit exposed to known attacks like POODLE and BEAST. Certificate validity and configuration security are two separate checks, and a site can pass one while failing the other. A proper check reports both, so "valid certificate" is never mistaken for "safe connection."

Expiry: A Preventable Outage

An expired certificate doesn't degrade gracefully — it throws a hard error for every visitor at once, taking your site down instantly. The checker shows the exact expiry date and a countdown of days remaining. This is especially important with Let's Encrypt, whose certificates last just 90 days and depend on auto-renewal that can silently fail after a DNS change or a broken cron job. Check regularly, treat anything under 30 days as urgent, and you'll never be caught out.

What the Checker Reports

Watch the Domain Coverage (SANs)

A certificate only secures the hostnames listed in its SANs. If a visitor reaches a host that isn't covered — most commonly the www versus non-www mismatch — the browser shows a "your connection is not private" error regardless of how valid the certificate otherwise is. Always re-check SANs after a renewal, since some automated tools quietly drop a subdomain that the previous certificate had.

Why It Matters for SEO and Trust

SSL isn't just a security concern. HTTPS is a Google ranking signal, and a site without a valid certificate displays a "Not Secure" warning that sends most visitors straight back to the results page. Valid SSL underpins user trust and secure payments, so a certificate check belongs in every SEO and security audit — and because the tool works on any domain, you can audit clients', partners', or competitors' sites just as easily as your own. Free, with no signup.

SSL Checker FAQs

What does an SSL checker do?

It opens a real secure connection to a domain, retrieves the SSL/TLS certificate the server presents, and reports the key details: whether the certificate is valid and trusted, when it expires and how many days remain, whether the certificate chain is complete, which domains it covers (SANs), who issued it, and which TLS version and ciphers the server negotiates. In short, it shows your site's encryption health as an outside visitor experiences it.

Why does a site work in my browser but fail the checker?

Almost always a missing intermediate certificate. Your browser may have cached the intermediate from another site and fills the gap silently, so the page looks fine to you. But a fresh client — a mobile app, a payment gateway, an API, a search crawler — has no such cache and rejects the connection. The checker validates the chain the way a first-time visitor would, which is why it catches the problem you can't see. The fix is to install the full chain (leaf plus intermediates) on the server.

Does a valid certificate mean my site is secure?

No — they're two separate things. A certificate proves identity and enables encryption, but a server with a perfect certificate can still negotiate obsolete protocols like TLS 1.0 or 1.1, weak ciphers, or be exposed to known vulnerabilities. A good checker reports both the certificate's validity and the configuration's security, so 'the certificate is valid' is never mistaken for 'the connection is safe.'

When does my SSL certificate expire, and why does it matter?

The checker shows the exact expiry date and a countdown of days remaining. This matters because an expired certificate produces a hard browser error for every visitor at once — instant, total downtime. Let's Encrypt certificates last only 90 days and rely on auto-renewal, which can silently fail due to a DNS change or a broken cron job. Checking regularly, and renewing under 30 days, prevents a very avoidable outage.

What are SANs and why should I check them?

SANs (Subject Alternative Names) are the exact hostnames a certificate covers. If the domain a visitor requests isn't listed — a common gap being www versus the bare domain — browsers reject the certificate even if the issuer and dates are perfect, throwing a 'your connection is not private' error. It's especially important to verify SANs after any renewal, since some automated tools issue new certificates that drop a subdomain from the old one.

Which TLS version should my server use?

TLS 1.2 and TLS 1.3 are the current, secure standards, with 1.3 being faster and stronger. SSL 2.0 and 3.0 are long dead, and TLS 1.0 and 1.1 were deprecated in 2020 — if your server still offers them, you risk security warnings and compliance failures like PCI DSS. The checker reports exactly which version is negotiated so you can disable the outdated ones.

Why does SSL matter for SEO and trust?

HTTPS is a confirmed Google ranking signal, and a site without a valid certificate shows a 'Not Secure' warning that drives most visitors away instantly. Beyond rankings, valid SSL is essential for user trust and for processing payments securely. Checking your certificate is part of any solid SEO and security audit — and you can check competitors' or partners' sites too.

Is the SSL checker free?

Yes, it's free with no signup. Enter any domain to inspect its live certificate details, diagnose errors, and confirm its encryption is configured correctly.