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SSL Certificate Checker

Inspect SSL/TLS certificate configurations for any public domain. Verify certificate authority issuers, expiration dates, cryptographic algorithms, and chain integrity to prevent security warnings.
✓ Free✓ No signup✓ Privacy first✓ Runs in your browser
SSL Certificate Checker - Verify TLS/SSL Online - ToolPremier
Target Hostname: - (Port 443 HTTPS)
Examples: google.com github.com cloudflare.com wikipedia.org
Paste Base64 / PEM Certificate:
Certificate Status
Details will appear here.
Certificate Status & Validity
Target Host: -
HTTPS Handshake: -
Days Remaining: -
Expires On: -
Issuer & Certificate Authority
Common Name (CN): -
Organization: -
CAA Policy (DNS): Checking DNS...
DNSSEC Validation: -
Protocols & Modern TLS Features
HTTP/3 & ALPN (HTTPS): -
HSTS Security: Enforced over HTTPS
Resolved IP Address: -
Subject Alternative Names (SAN)

How it works

Get it done in three steps

1. Enter the domain hostname

Type or paste the target web address or server hostname into the inspection field.

2. Initiate certificate scan

Click the check button to query public TLS handshake endpoints and retrieve active certificate details.

3. Review security parameters

Inspect validity dates, days remaining until expiration, subject alternative names, and certificate chain status.

FAQ

Common questions

When an SSL certificate expires, web browsers display prominent security warnings that block visitors from entering your site, resulting in lost traffic, broken checkout flows, and damaged user trust. Furthermore, search engines view active HTTPS encryption as an essential ranking criterion. Regularly verifying expiration timelines ensures certificates are renewed well ahead of downtime risks.
The tool evaluates multiple dimensions of your SSL implementation, including the issuing Certificate Authority (e.g., Let’s Encrypt, DigiCert, Cloudflare), the public key signature algorithm, validity start and end dates, and Subject Alternative Names (SANs). It also checks for common configuration mistakes like mismatched domain names or broken intermediate certificate chains.
Common SSL warnings often stem from intermediate certificate chain issues rather than an expired leaf certificate. If a web server fails to bundle intermediate certificates provided by the issuer, mobile devices and certain browsers cannot establish a trusted chain to the root authority. The audit highlights chain gaps so server administrators can fix configuration files.
All TLS checks route through secure public DNS and handshake diagnostic queries initiated from your browser session. Searched domains and technical reports are never archived in public search histories or stored in tracking databases. Refreshing the browser removes all audit records.

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About the SSL Certificate Checker

The SSL Certificate Checker is a diagnostic tool built for webmasters, DevOps engineers, and business owners to audit domain encryption health. It verifies that web properties have valid, trusted cryptographic certificates installed that protect visitor data in transit. By proactively flagging upcoming expirations and chain vulnerabilities, it helps organizations prevent preventable website outages.

Benefits

  • Prevent costly outages — monitor exact expiration dates and remaining days to renew SSL certificates before browser warnings trigger.
  • Validate certificate authority trust — confirm your certificate is signed by recognized authorities like Let's Encrypt or DigiCert.
  • Inspect Subject Alternative Names — verify that all required subdomains and domain variations are covered under the current certificate.
  • Diagnose intermediate chain flaws — identify missing trust chain certificates that cause handshake errors on mobile browsers.

Privacy

All SSL diagnostic checks are conducted through secure public endpoints, and no domain queries are logged or retained on our servers.