SSL certificate checker
Confirm that your site’s SSL/TLS certificate is valid, trusted, and actually protecting visitors. This free scan makes a real TLS connection and reports whether HTTPS is set up the way modern browsers expect.
Free, read-only, no signup. See our methodology.
In short
The scanner opens a genuine HTTPS connection to your site — the same handshake a browser performs — and verifies the certificate against the host. If the certificate is trusted and HTTPS is delivered, the check passes. If verification fails, we tell you the exact reason rather than inventing a result.
What the SSL check validates
Certificate checking is the heaviest single item in the scan, because a broken or missing certificate undermines everything else. Here is what the connection confirms.
Trusted certificate
We verify that the certificate chains to a trusted authority and matches the hostname — the same validation a browser does before showing the padlock.
HTTPS actually enforced
We check that the final response is served over HTTPS after any redirects, so visitors land on the encrypted version of your site.
The scan also records the HTTP protocol version negotiated on the connection, so you can see whether your server is using a modern stack. If the TLS handshake fails, the report includes the underlying error so you can act on it.
Why a valid certificate matters
A TLS certificate does two jobs: it encrypts the connection so data can’t be read in transit, and it proves the visitor is talking to your server rather than an impostor. When the certificate is missing, expired, or doesn’t match the domain, browsers replace the padlock with a full-page “Not secure” warning that scares visitors away and blocks features like HTTP/2 and modern APIs. Because certificate lifetimes keep shrinking, an expired cert is one of the most common — and most avoidable — reasons a working site suddenly breaks.
How to fix common SSL issues
- No certificate at all. Install one — a free Let’s Encrypt certificate is trusted by every major browser and renews automatically.
- HTTPS not enforced. Add a permanent 301 redirect from HTTP to HTTPS so no visitor stays on the insecure version.
- “Not secure” despite a certificate. Track down mixed content — images, scripts or styles loaded over plain HTTP — and switch those URLs to HTTPS.
- Certificate expiring. Automate renewal and monitor the expiry date so a lapse never takes your site offline.
SSL/TLS guides
What Is SSL/TLS? A Plain-English Guide
How SSL/TLS encryption actually works, why every website needs HTTPS, and what the padlock in the browser really proves.
Read guide →SSL / TLS & EncryptionTLS 1.3 Explained: What Changed and Why It Matters
A clear breakdown of TLS 1.3 — faster handshakes, forward secrecy, and how to check whether your site supports it.
Read guide →SSL / TLS & EncryptionHow to Fix Mixed Content Warnings
Why the padlock disappears on HTTPS pages and a step-by-step method to find and fix mixed content.
Read guide →Frequently asked questions
What does the SSL certificate checker verify?
It opens a real TLS connection to the site, verifies that the certificate is trusted and validates against the host, and confirms the site is actually served over HTTPS. If verification fails, it reports the reason honestly instead of guessing.
Do I need a paid SSL certificate?
For most websites a free certificate from a provider such as Let’s Encrypt is enough to be trusted by browsers. Organisation or extended validation certificates add verified identity, which some businesses want, but they are not required for encryption.
Why does my site show “Not secure” even with a certificate?
Usually because HTTPS is not enforced or the page loads some resources over plain HTTP — known as mixed content. Redirecting all traffic to HTTPS and fixing insecure resource URLs resolves it.