SSL Certificate Checker
Check SSL/TLS certificate information, expiration dates, and security details for any domain
What is SSL/TLS?
SSL/TLS certificates protect web traffic by encrypting connections between browsers and servers. HTTPS sites build trust and are favored by modern browsers and search engines alike.
SSL (Secure Sockets Layer) and its successor TLS (Transport Layer Security) are cryptographic protocols that secure internet communications. When a website has an SSL/TLS certificate installed, it enables HTTPS (the secure version of HTTP) and creates an encrypted tunnel between the web server and the visitor's browser.
How SSL/TLS Works
The SSL/TLS handshake process happens in milliseconds:
- Client Hello: Your browser connects to a website and requests a secure connection
- Server Response: The web server sends its SSL certificate and public key
- Certificate Verification: Your browser verifies the certificate against trusted Certificate Authorities (CAs)
- Key Exchange: Both parties generate session keys for symmetric encryption
- Secure Connection: All data transmitted is now encrypted and secure
Modern websites use TLS 1.2 or TLS 1.3 protocols exclusively, as earlier versions (SSL 2.0, SSL 3.0, TLS 1.0) have known security vulnerabilities. Despite this, the term "SSL certificate" persists in common usage.
Why HTTPS Matters Today
HTTPS has evolved from optional security enhancement to absolute necessity for any website operating in 2026.
Browser Security Warnings
Modern browsers actively warn users about non-HTTPS sites. Chrome, Firefox, Safari, and Edge all display prominent "Not Secure" warnings in the address bar when users visit HTTP sites. These warnings erode user trust and dramatically increase bounce rates.
SEO Impact: HTTPS as a Ranking Signal
Google confirmed HTTPS as a lightweight ranking signal in 2014, and its importance has only grown. Websites without SSL certificates face:
- Lower Search Rankings: HTTPS sites receive preferential treatment in search results
- Reduced Crawl Budget: Google may deprioritize crawling non-HTTPS sites
- Referrer Data Loss: HTTPS to HTTP referrals strip referrer information, breaking analytics
- Chrome Speed Boost: HTTP/2 and HTTP/3 protocols require HTTPS and offer significant performance gains
When Expired SSL Kills Trust
An expired SSL certificate triggers immediate, severe warnings in all browsers:
- Full-Page Warnings: Browsers display red warning screens before allowing access
- E-commerce Disaster: Customers will never enter payment information on a site with certificate errors
- SEO Penalties: Search engines may deindex pages with invalid certificates
- Lost Conversions: Studies show 85%+ of users abandon sites with SSL warnings
Regular SSL certificate monitoring prevents these catastrophic failures. Set up automated checks at least 30 days before expiration.
How This SSL Checker Works
Our SSL Certificate Checker performs a comprehensive analysis of your website's TLS configuration in real-time. Here's what happens behind the scenes:
Technical Process
- TLS Handshake Initiation: The tool establishes a TLS connection to your domain on port 443 (HTTPS)
- Certificate Chain Retrieval: Downloads the complete certificate chain from end-entity to root CA
- Validity Verification: Checks certificate dates, signature algorithms, and trust chain integrity
- Domain Validation: Confirms the certificate covers the requested domain and any Subject Alternative Names (SANs)
- Protocol Analysis: Identifies supported TLS versions and cipher suites
- Expiration Calculation: Computes exact days remaining until certificate expiration
What We Check
Certificate Validity
Confirms the certificate is currently valid, not expired, and issued by a trusted Certificate Authority
Domain Coverage
Verifies all domains and subdomains listed in the certificate's Subject Alternative Names field
Encryption Strength
Displays key size (2048-bit RSA minimum recommended) and signature algorithms for security assessment
Trust Chain
Validates the complete certificate chain from your certificate through intermediate CAs to the root CA
Unlike basic browser checks, our tool provides granular certificate details essential for developers, system administrators, and SEO professionals managing multiple domains.
Common SSL Errors & How to Fix Them
SSL certificate errors are frustrating but usually straightforward to resolve. Here are the most common issues and their solutions.
🔴 NET::ERR_CERT_DATE_INVALID
What it means: Your SSL certificate has expired or hasn't become valid yet.
How to fix:
- Check the expiration date using this tool above
- If expired, renew through your Certificate Authority or hosting provider
- For Let's Encrypt: Run
certbot renewon your server - For commercial certificates: Log into your CA account and initiate renewal
- After obtaining the new certificate, install it on your web server
- Restart your web server (nginx, Apache, etc.)
- Test with this SSL checker to verify the new certificate is active
🔴 NET::ERR_CERT_COMMON_NAME_INVALID
What it means: The certificate isn't issued for the domain you're visiting.
How to fix:
- Check if you're accessing www.example.com but certificate only covers example.com (or vice versa)
- Obtain a certificate that covers both domains, or use a wildcard certificate (*.example.com)
- For Let's Encrypt:
certbot --nginx -d example.com -d www.example.com - Update your redirect configuration to ensure consistent URL access
- Verify all domains in Subject Alternative Names (SANs) using this tool
🔴 NET::ERR_CERT_AUTHORITY_INVALID
What it means: The certificate isn't signed by a trusted Certificate Authority, or the certificate chain is incomplete.
How to fix:
- Self-signed certificates: Replace with a certificate from a trusted CA like Let's Encrypt (free) or commercial providers
- Missing intermediate certificates: Download the complete certificate chain from your CA
- For nginx: Combine certificates:
cat domain.crt intermediate.crt > fullchain.pem - For Apache: Set
SSLCertificateChainFileto point to intermediate certificates - Test the complete chain using SSL Labs or this checker
⚠️ Mixed Content Warnings
What it means: Your HTTPS page loads HTTP resources (images, scripts, stylesheets).
How to fix:
- Open browser Developer Tools (F12) → Console to see mixed content warnings
- Update all resource URLs from http:// to https://
- Use protocol-relative URLs:
//example.com/style.css(not recommended for modern sites) - Better: Use absolute HTTPS URLs or relative paths
- Check third-party scripts and CDNs support HTTPS
- Add Content Security Policy header:
upgrade-insecure-requests - Use link extraction tools to find all resource URLs
🔧 Installing Let's Encrypt (Free SSL)
For Ubuntu/Debian with nginx:
sudo apt install certbot python3-certbot-nginxsudo certbot --nginx -d yourdomain.com -d www.yourdomain.com- Follow prompts to agree to terms and provide email
- Certbot automatically configures nginx and enables HTTPS
- Test auto-renewal:
sudo certbot renew --dry-run
For Ubuntu/Debian with Apache:
sudo apt install certbot python3-certbot-apachesudo certbot --apache -d yourdomain.com -d www.yourdomain.com
⏰ Setting Up Auto-Renewal
Prevent expiration with automatic renewal:
- Let's Encrypt: Certbot installs a cron job automatically
- Verify:
sudo systemctl status certbot.timer - Manual renewal test:
sudo certbot renew --dry-run - Commercial certificates: Enable auto-renewal in your hosting control panel (cPanel, Plesk, etc.)
- Set calendar reminders 30 days before expiration as backup
- Monitor with this SSL checker weekly
SEO Impact of HTTPS: Why It's a Ranking Signal
HTTPS isn't just security theater—it's a documented Google ranking factor that directly impacts your search visibility.
Google's Official Stance
In August 2014, Google publicly announced HTTPS as a ranking signal. While initially described as a "lightweight" factor, its importance has grown substantially. Google's John Mueller has repeatedly confirmed that HTTPS provides a ranking advantage over identical HTTP content.
Measurable SEO Benefits
- Direct Ranking Boost: Independent studies show 1-5% ranking improvement after migrating to HTTPS, with competitive keywords seeing larger gains
- Trust Signals: The padlock icon in browsers increases click-through rates from search results by 10-15%
- Referrer Data Preservation: HTTPS to HTTPS traffic preserves referrer information, while HTTP breaks the referrer chain
- HTTP/2 & HTTP/3 Support: These faster protocols require HTTPS and provide significant page speed improvements
- Core Web Vitals: HTTPS enables performance optimizations that improve Core Web Vitals scores
- Mobile-First Indexing: Google's mobile-first index strongly prefers HTTPS sites
HTTPS Migration Best Practices for SEO
Migrating from HTTP to HTTPS requires careful execution to preserve search rankings:
- 301 Redirects: Implement server-side 301 redirects from all HTTP URLs to HTTPS equivalents (test with our redirect tester tool)
- Update Internal Links: Change all internal links to use HTTPS to avoid redirect chains
- Update Canonical Tags: Ensure all canonical tags point to HTTPS URLs
- Update XML Sitemaps: Submit new HTTPS sitemap to Google Search Console
- Update Robots.txt: Reference HTTPS sitemap URLs in robots.txt
- Search Console: Add HTTPS property and monitor for crawl errors
- HSTS Header: Implement HTTP Strict Transport Security after confirming everything works
- Update Structured Data: Ensure all Schema.org markup uses HTTPS URLs
Common HTTPS Migration Mistakes
- ❌ Using 302 redirects instead of 301 redirects
- ❌ Blocking HTTPS in robots.txt during migration
- ❌ Not updating internal links, causing redirect chains
- ❌ Mixed content errors breaking page functionality
- ❌ Forgetting to update CDN and third-party integrations
- ❌ Not monitoring search rankings during/after migration
Real-World SSL Certificate Examples & Use Cases
Understanding different SSL certificate types and their practical applications helps you choose the right solution.
E-commerce Site SSL Expiration
Scenario: An online store's SSL certificate expires during Black Friday weekend.
Impact:
- Browsers show full-screen warnings: "Your connection is not private"
- Customers cannot complete checkout—all abandon their carts
- Estimated revenue loss: $50,000-$500,000 depending on traffic volume
- Payment processors may suspend the merchant account for security violations
- SEO rankings drop as Google detects the invalid certificate
Prevention: Enable automatic renewal 60 days before expiration. Monitor certificates weekly with automated SSL checking tools. Maintain renewal calendar with multiple team member notifications.
Wildcard vs. Single-Domain Certificates
Use Case: A SaaS company with multiple subdomains.
Option 1: Single-Domain Certificates
- Coverage: Only covers www.example.com OR example.com (not both unless specified)
- Cost: $0-$200/year per domain
- Best for: Simple websites with 1-2 domains
- Example: Personal blog, small business site
Option 2: Wildcard Certificates (*.example.com)
- Coverage: Covers all first-level subdomains (app.example.com, blog.example.com, api.example.com)
- Cost: $100-$500/year, or free with Let's Encrypt
- Best for: Applications with multiple subdomains
- Limitation: Doesn't cover second-level subdomains (admin.app.example.com)
- Example: SaaS platforms, multi-tenant applications
Option 3: Multi-Domain (SAN) Certificates
- Coverage: Covers multiple specific domains (example.com, example.org, example.net)
- Cost: $150-$600/year for up to 100 domains
- Best for: Organizations managing multiple distinct domains
Mixed Content Warnings on News Site
Scenario: A news website migrates to HTTPS but embeds HTTP images from their legacy CMS.
Impact:
- Browsers show "Not Secure" warning despite valid SSL certificate
- Modern browsers block mixed content, breaking page layouts
- Images and videos fail to load, degrading user experience
- SEO rankings suffer as page quality signals deteriorate
Solution:
- Audit all resource URLs using browser DevTools Console
- Update CMS configuration to serve all assets via HTTPS
- Implement Content-Security-Policy header with
upgrade-insecure-requestsdirective - Use a link extraction tool to identify remaining HTTP resources
- Consider CDN with automatic HTTPS rewriting
Corporate Certificate Management
Use Case: Enterprise managing 200+ domains across departments.
Challenges:
- Tracking expiration dates across multiple vendors
- Different teams using different Certificate Authorities
- No centralized visibility into certificate status
- Frequent expiration-related outages
Solution:
- Centralized Certificate Management: Implement tools like AWS Certificate Manager or HashiCorp Vault
- Automated Monitoring: Set up daily SSL checks for all domains
- Standardization: Migrate to Let's Encrypt with automated renewal for non-critical domains
- Extended Validation (EV) for critical domains: E-commerce and authentication endpoints
- Alert System: Email/Slack notifications 60, 30, and 14 days before expiration
- Certificate Inventory: Maintain spreadsheet or database tracking all certificates, owners, and renewal dates
SSL Certificate Providers: Alternatives & Comparisons
Choosing the right Certificate Authority depends on your technical requirements, budget, and support needs.
| Provider | Cost | Validation Type | Best For | Auto-Renewal |
|---|---|---|---|---|
| Let's Encrypt | Free | Domain Validation (DV) | Most websites, blogs, small businesses | ✅ Yes (via certbot) |
| Sectigo (Comodo) | $8-$250/year | DV, OV, EV | Commercial sites needing insurance | ✅ Yes (some hosts) |
| DigiCert | $200-$1,500/year | DV, OV, EV | Enterprise, high-value transactions | ✅ Yes (enterprise plans) |
| GoDaddy SSL | $70-$300/year | DV, OV, EV | Small businesses using GoDaddy hosting | ⚠️ Partial |
| AWS Certificate Manager | Free (for AWS services) | DV | Sites/apps hosted on AWS | ✅ Fully automatic |
| Cloudflare SSL | Free-$200/month | DV, OV (custom plans) | Sites using Cloudflare CDN | ✅ Fully automatic |
Validation Types Explained
Domain Validation (DV)
Verification: Proves you control the domain (via email, DNS, or HTTP)
Issuance Time: Minutes to hours
Trust Indicator: Padlock icon only
Best For: 95% of websites—blogs, portfolios, small businesses, internal apps
Example: Let's Encrypt, AWS Certificate Manager
Organization Validation (OV)
Verification: Proves domain control + verifies legal organization existence
Issuance Time: 1-3 business days
Trust Indicator: Padlock + organization name in certificate details
Best For: Established businesses wanting additional credibility
Example: Sectigo OV, DigiCert OV
Extended Validation (EV)
Verification: Extensive vetting of legal, physical, and operational existence
Issuance Time: 1-2 weeks
Trust Indicator: Previously showed green address bar (removed in modern browsers)
Best For: Banks, e-commerce, high-value transactions (though value is debated post-2019)
Example: DigiCert EV, Sectigo EV
Note: Major browsers removed the green address bar in 2019, reducing EV's visual differentiation
Our Recommendation
For 90% of websites: Use Let's Encrypt. It's free, trusted by all browsers, supports wildcard certificates, and auto-renews via certbot. The encryption is identical to paid certificates.
When to pay for SSL:
- You need warranty/insurance coverage (commercial CAs offer up to $1.75M warranty)
- You require Organization Validation to display company name
- Your compliance requirements mandate specific CAs
- You need dedicated support for troubleshooting
Frequently Asked Questions
Everything you need to know about checking SSL certificates online
An SSL certificate checker is a free online tool that verifies and displays detailed information about a website's SSL/TLS certificate. You need an SSL checker to:
Verify Website Security: Confirm that a website has a valid SSL certificate installed, ensuring encrypted connections between users and the server.
Check Expiration Dates: SSL certificates typically expire after 90 days to 1 year. Regular checks prevent unexpected expiration that could cause security warnings for your visitors.
Validate Certificate Details: Verify the certificate issuer, encryption strength, domain coverage, and certificate chain to ensure proper security implementation.
Troubleshoot HTTPS Issues: When experiencing browser warnings or connection problems, an SSL checker helps identify misconfigurations, expired certificates, or chain validation errors.
For website owners, developers, and security professionals, regular SSL checks are essential for maintaining trust and search engine rankings, as Google prioritizes HTTPS sites in search results.
To check if your SSL certificate is working correctly, follow these steps:
1. Enter Your Domain: Type your domain name (e.g., example.com) into the SSL checker tool above. Don't include "https://" or "www" - the tool handles these automatically.
2. Review Certificate Status: Look for a green checkmark or "Valid" status. This confirms your certificate is active and properly configured.
3. Check Expiration Date: Verify your certificate won't expire soon. Most certificates last 90 days (Let's Encrypt) or 1 year (commercial CAs). Set renewal reminders at least 30 days before expiration.
4. Verify Certificate Chain: Ensure the intermediate and root certificates are properly installed. An incomplete chain causes trust errors in browsers.
5. Confirm Domain Coverage: Check that your certificate covers all intended domains and subdomains. Wildcard certificates (*.example.com) cover all subdomains, while standard certificates only cover specific domains.
Common Issues: Mixed content warnings, certificate name mismatches, expired certificates, or self-signed certificates will all trigger browser warnings and should be resolved immediately.
An "SSL certificate expired" error means your digital certificate has passed its validity period and browsers no longer trust it. Here's what happens and how to fix it:
Why Certificates Expire: SSL/TLS certificates have limited validity periods (typically 90 days for Let's Encrypt, up to 1 year for commercial certificates) to ensure security keys are regularly updated and maintain current security standards.
Impact on Your Website: Visitors see prominent security warnings like "Your connection is not private" or "NET::ERR_CERT_DATE_INVALID," causing most users to leave your site. This damages trust, reduces traffic, and hurts SEO rankings.
How to Fix It:
- Renew Through Your Provider: Contact your certificate authority (Let's Encrypt, Sectigo, DigiCert, etc.) or hosting provider to renew the certificate
- Automatic Renewal: Enable auto-renewal through your hosting control panel or certbot for Let's Encrypt certificates
- Reinstall the Certificate: After obtaining a new certificate, install it on your web server following your hosting provider's instructions
- Clear Browser Cache: After renewal, clear your browser cache and test in incognito mode to verify the new certificate is active
Prevention: Set up monitoring alerts 30 days before expiration, use automated renewal tools, and regularly check your certificate status with an SSL checker.
SSL (Secure Sockets Layer) and TLS (Transport Layer Security) are cryptographic protocols that secure internet connections, but TLS is the modern, more secure version:
Historical Context: SSL was the original protocol (SSL 2.0 in 1995, SSL 3.0 in 1996), but it had security vulnerabilities. TLS 1.0 was released in 1999 as SSL's successor, with TLS 1.2 (2008) and TLS 1.3 (2018) being current standards.
Key Differences:
- Security: TLS uses stronger encryption algorithms and improved security mechanisms. SSL 2.0 and 3.0 are now deprecated due to vulnerabilities like POODLE
- Performance: TLS 1.3 establishes connections faster with fewer round trips, improving website speed
- Modern Standards: All "SSL certificates" today actually use TLS protocols. The term "SSL certificate" persists due to historical naming
What You Should Know: When you buy or install an "SSL certificate," you're actually implementing TLS encryption. Modern servers should use TLS 1.2 or TLS 1.3 exclusively. Our SSL checker displays which TLS versions your server supports, helping you ensure you're using secure, up-to-date protocols.
For Website Owners: Disable SSL 2.0, SSL 3.0, and TLS 1.0 on your servers. Use only TLS 1.2 and TLS 1.3 for maximum security and compatibility with modern browsers.
You can check SSL certificate details completely free using our SSL Certificate Checker tool above. Here's what you get:
Instant Certificate Information:
- Validity Status: See if the certificate is currently valid, expired, or has issues
- Expiration Date: Know exactly when your certificate expires
- Issuer Details: Identify which Certificate Authority issued the certificate (Let's Encrypt, Sectigo, DigiCert, etc.)
- Domain Coverage: View all domains and subdomains covered by the certificate
- Encryption Strength: Check the key size (2048-bit RSA, 256-bit ECC) and signature algorithm
- Certificate Chain: Verify the complete trust chain from end-entity to root certificate
How to Use Our Free SSL Checker:
- Enter your domain name in the checker above (just the domain, like example.com)
- Click "Check SSL Certificate"
- Review comprehensive certificate details in seconds
- No registration, no credit card, no limits
For Developers: Our tool is perfect for quick checks during development, troubleshooting certificate issues, or monitoring multiple domains. Bookmark it for instant access whenever you need to verify SSL/TLS configurations.