SSL Checker

Check SSL certificate for any domain online — certificate chain, expiration date, issuer, protocol versions. Free SSL test to verify HTTPS is valid and properly configured.

Run a check to see results

APIPOST /api/v1/web/ssl
5(13 votes)
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Try also: HTTP Headers
Run Check

Key Features

100% Free

No registration required, unlimited checks

Instant Results

Real-time analysis with detailed output

REST API Access

Integrate into your workflow via API

Accurate Data

Live queries to authoritative sources

What is SSL Checker?

The SSL checker performs a comprehensive inspection of the SSL/TLS certificate for any domain. It connects to the server over HTTPS and verifies the complete certificate chain from the server certificate through intermediate certificates to the trusted root CA, checks the certificate expiration date, confirms the issuer is a recognized Certificate Authority, validates that the certificate matches the domain name (including wildcard and SAN entries), detects supported TLS protocol versions (1.0, 1.1, 1.2, 1.3), and identifies the cipher suites in use. This free SSL certificate checker is essential for website owners ensuring their HTTPS is properly configured, system administrators monitoring certificate expiration to prevent outages, SEO specialists verifying SSL setup (HTTPS is a Google ranking factor), security auditors checking for weak protocols or cipher suites, and DevOps teams validating certificates after renewal or deployment.

An expired or misconfigured SSL certificate triggers browser security warnings that block visitors and destroy trust — regular checking prevents this.

How to Use

  1. 1Enter the domain name to check its SSL certificate (e.g., example.com)
  2. 2Click 'Run Check' to connect to the server and inspect the certificate chain
  3. 3Review the certificate details: issuer, subject, validity dates, and serial number
  4. 4Check the certificate chain: server cert → intermediate cert(s) → root CA — all should be valid
  5. 5Verify TLS version support: TLS 1.2 and 1.3 should be enabled, TLS 1.0 and 1.1 should be disabled
  6. 6Note the expiration date and set a reminder to renew before it expires

Who Uses This

System Administrators

Monitor and troubleshoot infrastructure

Developers

Debug network issues and integrate via API

SEO Specialists

Verify domain configuration and performance

Security Analysts

Audit and assess network security

Frequently Asked Questions

How do I check if an SSL certificate is valid?
Enter the domain in the SSL Checker and run the check. The tool connects to the server and verifies multiple aspects: the certificate hasn't expired, the issuer is a trusted Certificate Authority, the certificate matches the domain name (checking Common Name and Subject Alternative Names), the full chain of trust is intact from server certificate to root CA, and no certificates in the chain have been revoked. A valid certificate means all these checks pass — any failure will be clearly flagged with the specific issue.
What happens when an SSL certificate expires?
When an SSL certificate expires, browsers immediately display a full-page security warning (like 'Your connection is not private' in Chrome or 'Warning: Potential Security Risk Ahead' in Firefox) that blocks visitors from reaching your site. Most users will leave rather than bypass the warning. The impact includes: immediate loss of website traffic, broken API integrations that validate certificates, loss of customer trust, potential SEO ranking drops (Google penalizes sites with invalid HTTPS), and failed payment processing (PCI compliance requires valid certificates). Set up automatic renewal with your certificate provider or use Let's Encrypt for free auto-renewing certificates.
What is the difference between SSL and TLS?
SSL (Secure Sockets Layer) was the original encryption protocol for web traffic, but it has been deprecated due to security vulnerabilities. TLS (Transport Layer Security) is its successor — TLS 1.2 (2008) and TLS 1.3 (2018) are the current standards. The term 'SSL certificate' persists in common usage, but technically all modern websites use TLS. TLS 1.3 is the fastest and most secure version, with a simplified handshake that reduces connection latency. TLS 1.0 and 1.1 are deprecated and should be disabled on all servers, as they contain known vulnerabilities.
What is a certificate chain and why does it matter?
A certificate chain (or chain of trust) is the hierarchy of certificates from your server's certificate up to a trusted root Certificate Authority (CA). It typically has three levels: your server certificate (issued specifically for your domain), an intermediate certificate (issued by the root CA to the entity that signed your certificate), and the root CA certificate (pre-installed in browsers and operating systems). If any link in this chain is missing, expired, or untrusted, browsers will show a security warning even if your server certificate itself is valid. The SSL Checker verifies the complete chain.
Does SSL affect SEO and search engine rankings?
Yes — Google confirmed HTTPS as a ranking signal in 2014, and it has become increasingly important since. Websites with valid SSL certificates get a ranking boost over HTTP-only sites. Beyond rankings, Chrome and other browsers mark HTTP sites as 'Not Secure' in the address bar, which reduces click-through rates and user trust. Modern web features like HTTP/2, service workers, and many browser APIs also require HTTPS. For any website that wants to rank well and maintain user trust, a valid SSL certificate is not optional — it's a fundamental requirement.

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API Endpoint

POST /api/v1/web/ssl
View Documentation