What is the SSL Checker?

An SSL certificate is a digital credential that enables HTTPS on a website — encrypting traffic between the browser and server and authenticating that the site is who it claims to be. When a certificate is missing, expired, misconfigured, or issued by an untrusted authority, browsers display security warnings that drive visitors away and damage trust.

The SSL Checker inspects the SSL certificate of any domain and returns the key details: validity, issuer, expiry date, protocol version, cipher strength, and whether the certificate chain is complete.

---

How to Use the SSL Checker

1. Enter the domain you want to check — just the domain name (example.com), without https:// or paths.
2. Run the check. The tool connects to the server over HTTPS, retrieves the certificate, and analyzes its configuration.
3. Review the results. Certificate details are displayed along with any warnings or issues detected.

---

What the SSL Checker Reports

Validity status — whether the certificate is currently valid, expired, or not yet valid. An expired certificate causes immediate browser warnings for all visitors.

Issuer / Certificate Authority — which CA signed the certificate: Let's Encrypt, DigiCert, Sectigo, ZeroSSL, and others. All major browsers trust certificates from recognized CAs.

Expiry date and days remaining — how long before the certificate expires. Set a renewal reminder at least 30 days before expiry. Most CAs allow renewal 30–90 days early. Let's Encrypt certificates expire every 90 days and should be auto-renewed.

Protocol version — the TLS version negotiated: TLS 1.3, TLS 1.2, or older (TLS 1.0/1.1 and SSL 3.0 are deprecated and insecure). TLS 1.3 is the current standard.

Cipher suite — the encryption algorithm used for the connection, such as TLS_AES_256_GCM_SHA384. Modern cipher suites with ECDHE key exchange and AES-GCM provide forward secrecy.

Certificate chain — a valid SSL configuration requires a complete chain: your site's certificate, any intermediate certificates, and a root certificate trusted by browsers. A missing intermediate certificate causes validation failures on some browsers and devices even when the certificate itself is valid.

Domain coverage — whether the certificate covers the domain being checked, including www and non-www variants if applicable. Wildcard certificates (*.example.com) cover all subdomains at one level.

---

Common SSL Issues and Fixes

Expired certificate — renew immediately. Most hosting providers and CAs have one-click renewal. For Let's Encrypt, enable auto-renewal via Certbot or your hosting panel.

Certificate not trusted — the issuer may not be in the browser's trusted root store, or an intermediate certificate is missing from the server. Download and install the complete certificate chain from your CA.

Domain mismatch — the certificate's Common Name (CN) or Subject Alternative Names (SANs) don't include the domain being accessed. Issue a new certificate that covers the correct domains.

TLS 1.0/1.1 still supported — disable older TLS versions in your server configuration. Most modern browsers no longer accept connections below TLS 1.2.

Weak cipher suites — update your server's cipher suite list to prioritize TLS 1.3 ciphers and remove deprecated options like RC4 and 3DES.

---

Privacy

Certificate checks are performed against publicly accessible server endpoints. No domain names entered or certificate details retrieved are stored or logged.