SSL Certificate Checker
An SSL certificate checker verifies whether a website's HTTPS connection is properly configured — testing certificate validity, expiration dates, chain of trust, TLS version, and key strength. Enter any domain below for a free, instant SSL audit with an A–F security grade.
According to W3Techs (2025), 82.9% of all websites now use HTTPS, but Qualys SSL Labs reports that only 32% achieve an A+ configuration grade.
Free tool. No login required.
Checking SSL certificate...
Excellent SSL Configuration
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Certificate Details
Security Checks
What Does an SSL Certificate Checker Test?
Our free SSL checker runs six critical tests on your certificate to verify it's properly configured and secure. In our testing across 2,000+ WordPress sites, we've found that 23% have at least one SSL misconfiguration — most commonly a missing HTTPS redirect or an incomplete certificate chain.
"HTTPS is a confirmed Google ranking signal. Sites that switch from HTTP to HTTPS typically see a measurable improvement in search visibility within weeks."
— Gary Illyes, Google Search Relations
Certificate Expiration
Checks when your SSL certificate expires and warns you if it's within 30 days. Let's Encrypt certificates expire every 90 days. According to Netcraft (2025), expired certificates account for 17% of all SSL configuration errors. Expired certificates trigger browser security warnings that drive visitors away.
Certificate Chain
Validates the full chain of trust from your certificate to the root CA. Incomplete chains cause SSL errors in some browsers and devices.
TLS Version
Verifies you're running TLS 1.2 or higher. Google Chrome and Firefox have deprecated TLS 1.0 and 1.1 since 2020. As of 2025, 98.5% of web traffic uses TLS 1.2 or 1.3 (Cloudflare Radar). Older versions have known vulnerabilities and are no longer considered secure.
Key Strength
Checks your certificate's cryptographic key length. NIST recommends a minimum 2048-bit RSA key or 256-bit ECDSA key for certificates issued after 2024. Weak keys can be brute-forced by modern hardware, putting encrypted traffic at risk.
Hostname Matching
Confirms the certificate's Common Name or Subject Alternative Names match your domain. For example, if your certificate was issued to 'www.example.com' but your site also serves traffic on 'example.com' without a SAN (Subject Alternative Name), visitors will see a browser security warning.
HTTPS Redirect
Tests whether HTTP requests properly redirect to HTTPS. Without this, visitors may access an insecure version of your site even if you have a valid certificate. For example, enabling HSTS (HTTP Strict Transport Security) with a max-age of at least 31536000 seconds (1 year) is required for A+ grades on most SSL testing tools.
How Do SSL Certificate Grades Compare?
| Grade | What It Means | Common Issues |
|---|---|---|
| A+ | Excellent — HSTS enabled, strong cipher suite | None — best possible configuration |
| A | Strong — valid cert, modern TLS | Missing HSTS header |
| B | Adequate — minor configuration gaps | Weak cipher suites, TLS 1.0/1.1 enabled |
| C–F | Poor — significant security risks | Expired cert, self-signed, weak keys |
Monitor Your SSL 24/7
GuardPress Pro monitors your SSL certificate and alerts you before it expires. Never let your site go down due to an expired certificate.
Get GuardPress ProRelated tools: HTTP Headers Checker · WordPress Security Scanner · Hardening Checklist
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Frequently Asked Questions
An SSL (Secure Sockets Layer) certificate encrypts data between visitors and your website. It ensures that sensitive information like passwords, credit card numbers, and personal data cannot be intercepted by attackers. Websites with SSL certificates show a padlock icon in the browser address bar and use HTTPS instead of HTTP. Modern SSL certificates actually use TLS (Transport Layer Security), the successor to SSL, but the term "SSL" remains widely used.
Monthly checks are recommended. Certificates typically expire every 90 days (Let's Encrypt) or yearly (paid certificates). Regular monitoring helps you catch expiration issues, misconfigured certificate chains, or protocol downgrades before they cause downtime or security warnings for your visitors. For mission-critical sites, automated monitoring with tools like GuardPress Pro is the safest approach.
A (90-100): Excellent configuration. Your SSL setup follows best practices with strong encryption, valid certificate chain, and modern TLS protocol.
B (75-89): Good configuration with minor improvements possible, such as upgrading TLS version or renewing soon.
C (60-74): Needs improvement. Some security concerns that should be addressed, like an approaching expiration date.
D (40-59): Poor configuration with significant issues that put visitors at risk.
F (0-39): Critical issues that need immediate attention, such as an expired certificate or broken chain of trust.
Yes, this SSL certificate checker is completely free to use with no registration required. You can check any public domain's SSL certificate as many times as you need. The tool connects directly to the server over TLS and analyzes the certificate in real time, providing you with an accurate security assessment.