SSL Certificate Checker
Verify SSL certificate validity, expiry dates, and HTTPS configuration for any website instantly.
What is SSL Certificate Checker?
An SSL (Secure Sockets Layer) certificate establishes an encrypted connection between a web server and a browser, ensuring all data transmitted between them is private and secure. HTTPS (HTTP Secure) — the lock icon in your browser's address bar — is powered by SSL/TLS certificates. Google has used HTTPS as a ranking signal since 2014, and Chrome marks all HTTP (non-secure) pages with a "Not Secure" warning that visibly erodes user trust. Beyond the basics, SSL misconfiguration is a common source of hard-to-diagnose issues: expired certificates cause browser warnings that block visitors, certificate chain errors cause security tools to fail, and mixed content (HTTPS page loading HTTP resources) triggers browser warnings despite a valid certificate. This tool checks any domain's SSL certificate in real time, reporting validity status, expiry date, issuer authority, cipher strength, and common configuration errors.
How to Use SSL Certificate Checker
- 1
Enter a Domain Name
Type any domain name (e.g. example.com) — no need to include https://. The tool connects to the server and retrieves the SSL certificate details.
- 2
Review Certificate Details
See the certificate's validity status, expiry date (with days remaining), issuer (CA), subject alternative names (SANs), and protocol/cipher suite information.
- 3
Check for Issues
The tool flags common problems: expired or soon-to-expire certificates, untrusted or self-signed certificates, certificate/domain name mismatches, and weak cipher configurations.
Use Cases
Preventing SSL Expiry Downtime
A forgotten SSL certificate expiry is one of the most common causes of sudden website downtime — browsers show a full-screen "Your connection is not private" warning that prevents most users from proceeding. Running weekly checks on all your certificates and setting calendar reminders 30 days before expiry prevents this easily avoidable issue.
Post-Migration HTTPS Verification
After migrating a site to a new server or CDN, verify that SSL is correctly configured on the new infrastructure before updating DNS. Common post-migration issues include missing intermediate certificates, certificate-domain mismatches, and old certificates not transferred to the new server.
Client Site Audits
Web agencies include SSL checks in every technical SEO audit. An expired or misconfigured certificate on a client's site causes both a Google ranking penalty and visible security warnings that drive users away — and the client often isn't aware until a visitor complains. This tool provides instant documentation of the SSL status for audit reports.
Features
Certificate Validity Check
Instantly confirms whether the SSL certificate is valid, expired, self-signed, or untrusted — with a clear pass/fail status and the reason for any failures.
Expiry Date Monitoring
Shows the exact expiry date and days remaining. Warnings trigger at 30 and 7 days remaining so you can renew before the certificate expires and causes visitor warnings.
Certificate Chain Verification
Checks that the complete certificate chain (leaf → intermediate → root CA) is correctly installed — a missing intermediate certificate is a common cause of SSL errors in some browsers.
SAN and Wildcard Coverage
Lists all Subject Alternative Names (SANs) covered by the certificate, so you can verify that all your subdomains and domains are included in the certificate scope.
Frequently Asked Questions
Yes. Google confirmed HTTPS as a ranking signal in 2014. It is described as a "lightweight" signal — not strong enough to overcome poor content or links on its own, but relevant as a tiebreaker between equally matched pages. More importantly, Chrome's "Not Secure" warning on HTTP pages significantly increases bounce rates, which indirectly harms rankings through user behaviour signals. Any website without HTTPS in 2024 is at a competitive disadvantage on both fronts.
SSL (Secure Sockets Layer) is the older protocol that was replaced by TLS (Transport Layer Security). SSL 2.0 and 3.0 are deprecated and insecure. TLS 1.0 and 1.1 are also deprecated. The current standard is TLS 1.2 (still widely used) and TLS 1.3 (the latest and fastest). Despite the terminology shift, the industry still commonly says "SSL certificate" when technically meaning a certificate used with TLS. When this tool reports "SSL certificate", it is checking the TLS configuration your server presents.
As of September 2020, the maximum SSL certificate validity period is 398 days (approximately 13 months). Most certificates are issued for 1 year. Let's Encrypt, the free certificate authority, issues 90-day certificates by default and recommends auto-renewal every 60 days for a comfortable buffer. Most modern hosting providers and CDNs (Cloudflare, AWS, Vercel, Netlify) handle SSL issuance and renewal automatically at no cost. If you manage your own server, set up automated renewal via certbot.
A mixed content warning occurs when an HTTPS page loads resources (images, scripts, stylesheets) over HTTP. Since the page is HTTPS but some resources are HTTP, the browser considers the page partially insecure. Chrome blocks mixed active content (scripts and stylesheets over HTTP) entirely and displays a shield icon for mixed passive content (images over HTTP). The fix is to update all resource URLs from http:// to https:// — or use protocol-relative URLs (//) that inherit the page's protocol.
A wildcard certificate covers a domain and all its immediate subdomains using an asterisk (*) in the domain field — e.g. *.example.com covers blog.example.com, shop.example.com, and api.example.com but NOT sub.blog.example.com (two levels deep). Wildcards are convenient for sites with many subdomains. Multi-domain (SAN) certificates cover specific multiple domains listed explicitly. A single-domain certificate only covers one domain (and optionally its www subdomain). This tool shows which type of certificate a domain uses and exactly which hostnames it covers.
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