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SSL Checker — Check SSL Certificate Online

Free SSL checker to test any website's SSL certificate. Check certificate validity, expiration date, issuer, certificate chain, TLS version, and cipher suite instantly. Our SSL certificate checker provides detailed security analysis for any domain.

Free SSL ToolSSL Certificate CheckTLS VersionExpiry Alerts
SSL Certificate Checker

Verify SSL certificate validity, expiration dates, and security details

What Is an SSL Certificate?

An SSL certificate (Secure Sockets Layer) is a digital certificate that authenticates a website's identity and creates an encrypted connection between the browser and the server. When a website has a valid SSL certificate, the URL starts with https:// and browsers display a padlock icon. SSL certificates protect sensitive data like login credentials, credit card numbers, and personal information from being intercepted by attackers.

Our free SSL checker online tool connects to any domain, retrieves the SSL certificate, and analyzes its security configuration. Unlike basic SSL testers, DNS Robot's SSL checker provides comprehensive details including the full certificate chain, TLS protocol version, cipher suite, Subject Alternative Names (SANs), server type detection, and hostname verification — everything you need for a complete SSL certificate check.

SSL checker showing certificate analysis with chain verification, TLS version, cipher suite, and security status
DNS Robot's free SSL checker provides complete certificate analysis including chain verification, TLS version, and security status.

How to Check SSL Certificate of Any Website

There are several ways to check an SSL certificate. Our online SSL checker is the fastest and most comprehensive method, but knowing alternatives is useful for system administrators.

How SSL certificates work showing TLS handshake between browser and server with certificate exchange and encryption
How SSL/TLS works: The browser verifies the certificate chain, negotiates encryption, and establishes a secure connection.
1
Online SSL Checker (Recommended)
Enter a domain name in our SSL checker above and click "Check SSL". The tool retrieves the certificate, analyzes the chain, checks TLS version, and displays all security details. No installation or technical knowledge required.
2
Browser Padlock Method
Click the padlock icon in your browser's address bar, then click "Certificate" or "Connection is secure". This shows basic certificate info (issuer, expiration) but lacks chain analysis and TLS details.
3
Command Line (OpenSSL)
Run openssl s_client -connect example.com:443 -servername example.com in Terminal. This shows raw certificate data — powerful but requires parsing the output manually.

SSL Certificate Types — DV, OV, and EV Explained

SSL certificates come in three validation levels. All provide the same encryption strength — the difference is how thoroughly the Certificate Authority verifies the organization's identity. Our SSL certificate checker identifies the certificate type for any domain.

DV

Domain Validated

Verifies domain ownership only. Issued in minutes. Used by most websites including those with free Let's Encrypt certificates. Lowest cost, basic trust level.

OV

Organization Validated

Verifies domain ownership plus organization identity. Issued in 1-3 days. Shows company name in certificate details. Used by businesses and organizations.

EV

Extended Validation

Highest verification: legal identity, physical address, operational existence. Issued in 1-2 weeks. Used by banks, financial institutions, and large enterprises.

Understanding the Certificate Chain

1
Leaf Certificate
Your server's SSL certificate. Contains your domain name, public key, and expiration date. This is what our SSL checker analyzes first.
2
Intermediate Certificate(s)
Issued by the CA to bridge between your certificate and the root. Missing intermediates cause "untrusted certificate" errors in browsers.
3
Root Certificate
Pre-installed in browsers and operating systems. Self-signed by trusted Certificate Authorities like DigiCert, Let's Encrypt, Sectigo, and GlobalSign.

Common SSL Certificate Errors

ERR_CERT_DATE_INVALID
Certificate has expired. Renew immediately and set up expiration monitoring with our SSL checker.
ERR_CERT_COMMON_NAME_INVALID
Hostname mismatch — the certificate doesn't cover the requested domain. Check SANs and consider a wildcard certificate.
ERR_CERT_AUTHORITY_INVALID
Untrusted or self-signed certificate. Install the complete certificate chain including intermediate certificates.
Mixed Content Warnings
HTTPS page loads HTTP resources. Update all asset URLs to HTTPS. Check with our HTTP Headers tool.

Why SSL Certificates Matter for SEO and Security

SSL certificates are no longer optional — they're essential for both security and search engine rankings. Here's why every website needs a valid SSL certificate:

SSL certificate comparison of DV, OV, and EV types with validation levels, issuance time, and trust indicators
SSL certificates impact SEO rankings, user trust, data security, and protocol support — use our SSL checker to verify your certificate.

Security Benefits

  • Data Encryption: SSL encrypts all data between browser and server, protecting passwords, credit cards, and personal information from interception.
  • Identity Verification: Certificates verify that the server belongs to the claimed organization, preventing phishing and man-in-the-middle attacks.
  • Data Integrity: SSL ensures data isn't modified in transit. Any tampering invalidates the connection, protecting against content injection.

SEO & Performance Benefits

  • Google Ranking Signal: HTTPS is a confirmed ranking factor. Sites with valid SSL certificates rank higher than HTTP-only competitors.
  • HTTP/2 & HTTP/3: Modern protocols require HTTPS, enabling multiplexing, header compression, and server push for faster page loads.
  • User Trust: The padlock icon and "Connection is secure" indicator increase conversion rates and reduce bounce rates.

SSL Certificate Best Practices

  • Use TLS 1.2 or 1.3 — disable older SSL/TLS versions
  • Enable HSTS to force HTTPS connections
  • Install the complete certificate chain (leaf + intermediates)
  • Use 2048-bit RSA or 256-bit ECDSA keys minimum
  • Set up automated certificate renewal (especially Let's Encrypt)
  • Add CAA DNS records to control which CAs can issue certificates
  • Redirect all HTTP traffic to HTTPS with 301 redirects
  • Monitor certificate expiration — check monthly with our SSL checker

Related Security & DNS Tools

DNS Lookup

Check all DNS records including CAA records that control SSL certificate issuance.

Domain Health

Comprehensive domain analysis including SSL, DNS, WHOIS, and email authentication.

HTTP Headers

Check HSTS, CSP, and other security headers that complement SSL protection.

WHOIS Lookup

Look up domain registrar, nameservers, expiration, and owner details via RDAP.

DNS Propagation

Check DNS propagation after updating records for SSL certificate validation.

IP Lookup

Look up IP geolocation, ISP, and hosting provider details for any server.

Frequently Asked Questions About SSL Certificates

An SSL checker is a tool that analyzes the SSL/TLS certificate installed on a website. DNS Robot's SSL checker connects to any domain over HTTPS, retrieves the SSL certificate, and reports on certificate validity, expiration date, issuer (Certificate Authority), certificate chain, TLS protocol version, cipher suite, Subject Alternative Names (SANs), and hostname match status. It helps website owners, developers, and security professionals verify that SSL certificates are properly configured and secure.