What is a certificate chain?

A certificate chain links your domain's end-entity certificate to a trusted root CA through one or more intermediate certificates. All links must be valid and trusted for browsers to accept the connection.

What are Subject Alternative Names (SANs)?

SANs are the list of domain names and subdomains a certificate is valid for. Modern certificates use SANs instead of the Common Name (CN) field, and a single certificate can cover hundreds of domains.

What does the SHA-256 fingerprint tell me?

The SHA-256 fingerprint is a unique hash of the certificate's content. You can use it to verify that the certificate you're seeing is exactly the one you expect — useful for certificate pinning and security audits.

Private by defaultRuns in your browser

SSL certificate checker

Enter a domain to fetch and inspect its live SSL/TLS certificate — including the full chain from end-entity to root CA.

Quick samples

SSL Checker

About this tool

View the full certificate chain, expiry date, issuer, Subject Alternative Names, fingerprints, and key type for any HTTPS domain. No signup.

Enter a domain to fetch and inspect its live SSL/TLS certificate — including the full chain from end-entity to root CA.

No signup requiredRuns in your browserInstant results

How to use

1
Enter a domain name (e.g. github.com) in the input field.
2
Click Check — the tool fetches the live SSL/TLS certificate from the server.
3
Review the certificate's validity period, issuer, and Subject Alternative Names.
4
Expand each certificate in the chain to inspect intermediate and root CA details.

Why use this tool?

→
Verify that a certificate covers all the expected subdomains via Subject Alternative Names.
→
Check how many days are left before a certificate expires so you can renew before downtime.
→
Inspect the full certificate chain to diagnose intermediate CA or trust issues.

ExamplesInput → output

Check expiry

Inputgithub.com

OutputValid until 2026-03-12 — 340 days remaining

Check SANs

Inputgoogle.com

OutputCovers: *.google.com, google.com, *.googleapis.com, ...

Inspect issuer

Inputdevtoolsforyou.com

OutputIssued by: Let's Encrypt R11 (3-cert chain)

Frequently asked questionsCommon questions answered

These answers explain common ssl checker tasks, expected input formats, and edge cases so both visitors and search engines can understand what this tool does.

What is a certificate chain?: A certificate chain links your domain's end-entity certificate to a trusted root CA through one or more intermediate certificates. All links must be valid and trusted for browsers to accept the connection.
What are Subject Alternative Names (SANs)?: SANs are the list of domain names and subdomains a certificate is valid for. Modern certificates use SANs instead of the Common Name (CN) field, and a single certificate can cover hundreds of domains.
What does the SHA-256 fingerprint tell me?: The SHA-256 fingerprint is a unique hash of the certificate's content. You can use it to verify that the certificate you're seeing is exactly the one you expect — useful for certificate pinning and security audits.