What is an SSL/TLS certificate?

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) certificates are digital certificates that authenticate a website's identity and enable an encrypted connection. They are essential for securing online communications, protecting sensitive data like login credentials, payment information, and personal details from being intercepted by malicious actors. Our SSL Checker tool helps you verify these certificates quickly and easily.

What is the difference between SSL and TLS?

TLS (Transport Layer Security) is the modern and more secure successor to SSL (Secure Sockets Layer). While the term 'SSL' is still widely used colloquially, the actual protocol securing your connection today is almost always TLS. Our tool checks the specific TLS version being used.

What is a Certificate Authority (CA)?

A Certificate Authority (CA) is a trusted third-party organization that issues digital certificates. Browsers and operating systems have a pre-installed list of trusted CAs (like Let's Encrypt, DigiCert, or GlobalSign). If a certificate is signed by a trusted CA, the browser will accept it as valid.

Why is checking an SSL certificate important?

Checking an SSL certificate helps verify that a website is authentic, that your connection to it is secure, and that your data is protected from eavesdropping. It's crucial for identifying potentially unsafe or fraudulent websites and ensuring your online activities are secure. It also helps website owners ensure their certificates are correctly configured and not expired.

What information does this SSL checker provide?

Our SSL checker provides comprehensive details about a certificate, including the subject (to whom it was issued), the issuer (who issued it), its validity period (start and end dates, days until expiration), Subject Alternative Names (SANs), TLS version, cipher suite, cipher strength, and more.

What does "Subject Alternative Names (SANs)" mean?

Subject Alternative Names (SANs) are an extension to SSL certificates that allow you to specify additional hostnames (sites, IP addresses, common names, etc.) to be protected by a single SSL certificate. For example, a single certificate can secure `www.example.com`, `example.com`, and `mail.example.com`.

How can I tell if my SSL certificate is about to expire?

Our tool checks the 'Valid To' date on your certificate and calculates the 'Days Until Expiration'. This gives you a clear indication of when you need to renew it. It's best practice to renew at least 30 days before the expiration date to avoid any service interruption.

What if a certificate is expired or invalid?

If a certificate is expired or invalid, your browser will typically display a warning message, and the connection may not be secure. This tool will flag such certificates. Website owners should renew or fix their certificates immediately to maintain security and user trust.

How often should I check my SSL certificates?

Website owners should regularly monitor their SSL certificates, especially as they approach their expiration date. Automated monitoring is recommended. For users, checking a site's SSL certificate is a good practice if you have any doubts about its authenticity or security, especially before submitting sensitive information.

What should I do if my website shows an SSL error?

An SSL error usually means the certificate has expired, is not configured correctly on the server, or does not match the domain name. Use this tool to identify the specific issue (e.g., expiration, name mismatch) and contact your web host or system administrator to resolve it.

What are TLS version and Cipher Suite?

TLS (Transport Layer Security) is the protocol that provides encryption. The TLS version indicates which version of the protocol is being used (e.g., TLS 1.2, TLS 1.3). A Cipher Suite is a set of algorithms that help secure a network connection using TLS. It includes algorithms for key exchange, bulk encryption, and message authentication. Stronger, modern versions and suites are preferred for better security.

SSL Certificate Checker

Is your connection secure? Instantly check any website's SSL/TLS certificate to verify its validity, issuer, and expiration.

Check SSL Certificate

Enter a domain name and port to verify its SSL/TLS certificate details.

SSL checks provide information based on current certificate status. For critical applications, always verify with the certificate authority.

Why SSL Certificate Health is Critical

An SSL/TLS certificate is the foundation of a secure website. It encrypts data, verifies your identity, and builds trust with your visitors. A misconfigured or expired certificate can drive users away and put data at risk.

Build User Trust

A valid SSL certificate (the padlock in the browser) is a universal sign of trust. It tells visitors that your site is authentic and their connection is secure.

Protect Sensitive Data

SSL encrypts all data sent between the user and your server, including logins, forms, and payment information, protecting it from eavesdroppers.

Avoid Browser Warnings

Expired or invalid certificates trigger scary security warnings in browsers, which can deter visitors and damage your brand's reputation.

Why Use Our SSL Checker?

SSL/TLS certificates are crucial for website security and user trust. Our SSL Checker tool helps you verify and monitor these certificates effectively. With our tool, you can:

Verify Certificate Validity: Quickly check if an SSL certificate is current, expired, or misconfigured.

Enhance Security Awareness: Understand the security level of websites you interact with or manage.

Prevent Browser Warnings: Ensure your website doesn't trigger "Not Secure" warnings, which can deter visitors.

Check Issuer Information: Identify the Certificate Authority (CA) that issued the certificate.

Inspect SANs: View all Subject Alternative Names covered by the certificate.

Monitor Expiration Dates: Keep track of when certificates need renewal to avoid service disruptions.

Detailed Connection Info: Check TLS version, cipher suite, and security strength.

SSL Checker Features

Real-time Validation

SSL/TLS certificate validation for any domain and port.

Comprehensive Details

Subject, Issuer, Serial Number, Version.

Validity Period

Includes days until expiration with progress bar.

SANs Listing

Subject Alternative Names (SANs) listing.

Certificate URIs

OCSP, CA Issuers, CRL Distribution Points.

Connection Details

TLS/SSL Protocol, Cipher Suite, Cipher Strength, and Security Level.

User-Friendly & Responsive

Clear, categorized results, for desktop and mobile.

Who Should Use This Tool?

Website Owners & Admins

To regularly verify and maintain their website's SSL certificate health.

IT & System Administrators

For routine checks, audits, and monitoring SSL certificates.

Security Professionals

To assess and validate SSL certificate configurations in audits.

Web Developers

To ensure SSL certificates are correctly implemented.

Curious Internet Users

To check the security status of websites they visit.

Always ensure your SSL certificates are up-to-date and correctly configured to protect user data and maintain trust.

Understanding SSL Certificate Details

When you check an SSL certificate using our tool, you receive detailed information about the certificate's properties and status. Here's what each detail means:

Subject: Information about the entity the certificate was issued to (e.g., domain name, organization).

Issuer: The Certificate Authority (CA) that issued the SSL certificate. CAs are trusted entities that verify the identity of the certificate requester.

Serial Number & Version: Unique identifiers for the certificate.

Valid From / Valid To: The date range during which the certificate is valid. After the "Valid To" date, the certificate expires and needs to be renewed.

Days Until Expiration: The number of days remaining until the certificate expires. It's important to renew the certificate before it expires to maintain a secure connection.

Subject Alternative Names (SAN): Additional domain names or IP addresses that the SSL certificate covers. This is useful for securing multiple domains with a single certificate.

OCSP URIs, CA Issuers, CRL Distribution Points: URLs related to certificate status checking and chain validation.

TLS Version & Cipher Suite: Details about the secure connection parameters established with the server.

Cipher Strength & Security: An indication of the connection's encryption strength.

For a deeper understanding of SSL certificates, consider exploring resources on web security and SSL/TLS technology.

Advanced Usage & Tips

Check Subdomains: Remember to check SSL certificates for all critical subdomains (e.g., www., mail., shop.). A wildcard certificate (*.example.com) or a multi-domain (SAN) certificate can cover these.

Check Non-Standard Ports: Use the port input field to check SSL/TLS on services running on ports other than 443 (e.g., secure email servers, custom applications).

Understand Certificate Chains: An SSL certificate is typically part of a chain of trust: Root CA -> Intermediate CA -> Your Domain Certificate. Ensure the full chain is correctly installed on your server.

CAA Records: Consider setting up DNS Certification Authority Authorization (CAA) records to specify which CAs are authorized to issue certificates for your domain, adding an extra layer of security.

HTTP Strict Transport Security (HSTS): Implement HSTS to instruct browsers to only connect to your site via HTTPS, preventing downgrade attacks.

Regular Audits: Beyond simple checks, perform comprehensive SSL/TLS server configuration audits using tools like SSL Labs' SSL Test to identify vulnerabilities.

Automate Renewals: Where possible, use automated certificate renewal processes (e.g., with Let's Encrypt and Certbot) to avoid accidental expirations.

Trust, Quality & Data Transparency

Expertise & Experience

TLS deployment & incident response (expired / mis‑chained / weak cipher) knowledge informs grading heuristics. We designed the SSL Checker features around realistic operational workflows.

Data Sources

Live TLS handshakes (OpenSSL), certificate chain building, OCSP / CRL checks, SCT presence, protocol / cipher enumeration and CT log references.

Update Cadence & Quality

Cipher / deprecation policy list reviewed weekly; vulnerability advisories trigger immediate rule updates. The rating component reflects genuine user feedback (one rating per browser client ID) and is filtered for abuse.

Privacy & Ethics

Hostnames tested are not permanently logged; only anonymized error tallies retained for reliability tracking. See our Privacy Policy for details. No personal account is required.

Accountability

Questions or accuracy concerns? Reach out via the Contact page or learn more About Us. We iterate quickly based on feedback.

Frequently Asked Questions (FAQ)

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