SSL Certificate Checker
Check SSL/TLS certificate details for any domain. View issuer information, expiry date, subject alternative names, and the full certificate chain.
Key Features
Certificate Details
View issuer, subject, validity period, and signature algorithm for any domain's SSL certificate.
SAN Coverage
Check all Subject Alternative Names (SANs) to see which domains are covered by the certificate.
Real-Time Check
Instantly fetch and display certificate data for any public domain using a secure API.
Chain Analysis
View the complete certificate chain from the server certificate to the root CA.
Frequently Asked Questions
Getting Started
How does the SSL checker work?
Enter a domain name and the tool fetches the SSL/TLS certificate details using a backend API. It displays the issuer, validity dates, subject, SANs, and certificate chain information.
Is this tool free?
Yes. The SSL checker is completely free. Note that certificate data is fetched from a public API and subject to rate limits.
Usage Tips
What information can I get from an SSL certificate?
An SSL certificate contains the domain name, issuing CA, validity period, public key, subject alternative names, and the signature algorithm. This tool displays all of these details.
Why would I need to check an SSL certificate?
Regular SSL checks help ensure your certificates haven't expired, been revoked, or misconfigured. It's essential for security audits, troubleshooting HTTPS issues, and verifying certificate chains.
Advanced
What is a certificate chain?
A certificate chain is a sequence of certificates from the server certificate up to the root CA. Each certificate in the chain is signed by the next one, establishing trust. The browser verifies this chain against its trusted root store.
What is a Subject Alternative Name (SAN)?
SANs are additional domain names listed on a certificate. A single certificate can secure multiple domains (e.g., example.com, www.example.com, api.example.com) through SAN entries. Modern browsers require SANs for all certificates.
How often should I check my SSL certificates?
It is recommended to check SSL certificates at least once a month and before renewal dates. For production environments, set up automated monitoring to alert you before expiration. Many certificates are valid for 90 days to 1 year.
What happens when an SSL certificate expires?
When an SSL certificate expires, browsers display security warnings and may block access to the site entirely. Users will see "Your connection is not private" warnings, which can severely impact traffic and trust. Automated renewal is strongly recommended.
What is the difference between DV, OV, and EV certificates?
DV (Domain Validation) verifies domain ownership only. OV (Organization Validation) also verifies the organization. EV (Extended Validation) requires the most thorough verification and displays the organization name in the browser address bar. DV is common for most websites.
Can I check SSL for internal or localhost domains?
This tool checks certificates via public Certificate Transparency logs, so it only works for publicly trusted certificates. Internal domains or self-signed certificates used on localhost or private networks cannot be checked through this method.