🔒 Domain ✅ 100% Free ⚡ Live Check

SSL Certificate Checker

Instantly verify SSL/TLS certificates for any domain. Check expiry dates, issuer details, Subject Alternative Names, certificate chain, key strength, and get an overall security grade.

Enter domain to check

Try: github.com google.com cloudflare.com stackoverflow.com

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Certificate Validity —

Issued: — Expires: —

📋 Certificate Details

Common Name

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Organisation

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Issued By

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Certificate Version

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Signature Algorithm

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Key Algorithm

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Key Size

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Serial Number

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🌐 Subject Alternative Names

🔗 Certificate Chain

🔏 SHA-256 Fingerprint

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📊 Certificate Stats

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Days left

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SANs

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Key bits

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Chain depth

🏆 Grade Scale

A+

Excellent — strong key, valid cert, no issues

B+

Good — expires within 30 days

Fair — expires within 14 days

Weak key (<2048-bit) or SHA-1 signature

Expired certificate

💡 SSL Tips

🔄

Auto-renew your cert at least 30 days before expiry to avoid downtime.

🔑

Use RSA 2048+ or EC 256-bit keys. Anything smaller is considered weak.

🌐

Wildcard certs (*.example.com) cover all subdomains with a single certificate.

🆓

Let's Encrypt offers free, auto-renewing SSL certs trusted by all major browsers.

🔗 Related Tools

What Does an SSL Certificate Checker Do?

An SSL certificate checker connects to a domain on a specified port (default 443), completes a TLS handshake, and extracts all the metadata from the server's certificate. This includes the certificate's expiry date, the Certificate Authority (CA) that issued it, the domains it covers (SANs), the cryptographic key type and strength, and the full certificate chain back to the root CA.

This tool performs a live, real-time check — it contacts the actual server each time, so you always get the current certificate, not a cached result.

Why SSL Certificate Monitoring Matters

Expired certificates cause browsers to show a full-page security warning, immediately destroying user trust and search rankings.
Misconfigured chains can cause failures on mobile devices and older clients even if the cert itself is valid.
Weak key sizes (RSA < 2048-bit) are rejected by modern browsers and CA/Browser Forum standards.
SHA-1 signatures are deprecated — any cert signed with SHA-1 is rejected by Chrome, Firefox, and Safari.
Wildcard vs SAN coverage — verify your cert actually covers all the subdomains your site uses.

Frequently Asked Questions

A Subject Alternative Name (SAN) is an extension that lets a single SSL certificate cover multiple domain names. For example, a cert might cover example.com, www.example.com, and api.example.com all at once. Modern certificates use SANs instead of (or in addition to) the Common Name field.

SSL certificates form a chain of trust: your server's certificate is signed by an Intermediate CA, which is signed by a Root CA. Browsers trust the Root CA (pre-installed), and verify the chain downward. If any intermediate cert is missing from the chain your server sends, some clients will reject the connection even though the end certificate is valid.

If using Let's Encrypt, run `certbot renew` on your server. For paid certs, purchase a renewal from your CA and re-issue. Then install the new cert on your web server (Apache, Nginx, etc.) and reload the server. The entire process takes 5–15 minutes with Let's Encrypt.

DV (Domain Validated) only confirms domain ownership — fastest and cheapest (Let's Encrypt). OV (Organisation Validated) also verifies the legal organisation — better for businesses. EV (Extended Validation) involves the most thorough vetting and historically showed a green bar in browsers, though most browsers have removed the visual distinction. For most websites, DV is sufficient.

Yes — change the port number in the port field next to the domain input. Common SSL ports include 443 (HTTPS), 465 (SMTPS), 636 (LDAPS), 993 (IMAPS), 995 (POP3S), and 8443 (alternative HTTPS). The checker will attempt a TLS connection on whatever port you specify.

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What is SSL Certificate Checker?

SSL Certificate Checker is a free online utility designed to help developers, designers, and technical professionals work more efficiently. This tool runs entirely in your browser — no installation required, no data sent to any server.

How to Use SSL Certificate Checker

Paste or type your input in the editor area above.
Click the action button to process your content.
Copy the output or download the result.

Key Features

100% Free — No registration or payment required.
Client-side Processing — Your data never leaves your browser.
Instant Results — Get output in milliseconds.
No Installation — Works directly in your web browser.
Mobile Friendly — Works on phones, tablets, and desktops.

Who Uses SSL Certificate Checker?

This tool is widely used by web developers, software engineers, data analysts, students, and IT professionals who need a quick and reliable way to process data without setting up complex software environments.

Frequently Asked Questions

Is SSL Certificate Checker free to use?

Yes, SSL Certificate Checker is completely free. There are no hidden charges, no subscription fees, and no account required.

Is my data safe when using SSL Certificate Checker?

Absolutely. All processing happens locally in your browser. No data is uploaded to any server, making it completely private and secure.

Can I use SSL Certificate Checker on mobile devices?

Yes, SSL Certificate Checker is fully responsive and works on all modern browsers and devices including smartphones and tablets.

Do I need to install anything to use SSL Certificate Checker?

No installation is required. Simply open the page in your browser and start using it immediately.

How accurate is SSL Certificate Checker?

SSL Certificate Checker uses industry-standard algorithms to ensure accurate and reliable results every time.