Short answer. For a one-off SSL check, use Qualys SSL Labs (the deepest free analysis of protocols and ciphers) or the enterno.io SSL checker (a fast report on expiry, chain of trust and supported TLS versions). DigiCert and SSL Shopper are great for quick chain diagnostics, while Hardenize and testssl.sh suit technical server-configuration audits. Your choice depends on whether you need depth, speed, or continuous monitoring.
Why check an SSL certificate
An SSL check answers several questions at once: has the certificate expired, is the chain of trust valid up to the root CA, which TLS versions does the server support, and are any weak ciphers enabled. A fault in any of these triggers the browser's "Your connection is not private" warning, hurts conversion, and can dent search rankings, since SSL/TLS проверку remains a ranking factor. For background on how certificates and chains work, see our SSL/TLS guide.
Tip: check your SSL at least 14 days before it expires — reissuing and propagating a new certificate across CDN and caches takes time, while an expired certificate blocks access to your site instantly.
If you have shell access to the server, you can see the full report on protocols, ciphers and the chain straight from a terminal, without sending data to a third party:
openssl s_client -connect example.com:443 -servername example.comThe command opens a TLS connection and prints the presented certificate chain, the negotiated protocol and cipher — a quick way to confirm the server serves a complete chain and modern TLS.
People usually reach for a checker in three situations: right after installing a certificate, when a browser error appears, and during a scheduled security audit. If you're facing a specific error, start with our fix for an expired SSL certificate — it covers the most common cases, including an incomplete chain and server clock skew.
SSL checker comparison
| Tool | Depth of analysis | Speed | Monitoring | Price |
|---|---|---|---|---|
| Qualys SSL Labs | Very high (A–F grade) | Slow (1–2 min) | No | Free |
| enterno.io | High | Fast | Yes | Free tier |
| DigiCert SSL Checker | Medium | Fast | No | Free |
| SSL Shopper | Medium | Fast | No | Free |
| Hardenize | High | Medium | Partial | Free / paid |
| testssl.sh | Very high | Depends on run | No | Open source |
Tool overview
- Qualys SSL Labs — the gold standard for deep analysis. It assigns an overall grade from A+ to F, checks for known vulnerabilities (BEAST, POODLE, Heartbleed), chain completeness, protocol parameters and forward secrecy. The trade-off is a slow scan and no time-based monitoring: it's a snapshot, not surveillance.
- enterno.io — an online SSL checker with a fast report: expiry, issuer, chain of trust, and supported TLS versions. Its strength is the pairing with continuous monitoring: put a domain under watch and get alerts before the certificate expires. The free tier offers 10 monitors, and it accepts RU cards.
- DigiCert SSL Checker — a simple, fast tool from a major certificate authority, handy for basic chain diagnostics and verifying the domain-name match.
- SSL Shopper — a popular free checker with a clear view of intermediate certificates, useful for spotting incomplete-chain problems that aren't visible in every browser.
- Hardenize — analyses not just TLS but the whole domain security stack (DNSSEC, headers, email protection). A good fit when you need a comprehensive audit rather than just the certificate.
- testssl.sh — an open-source command-line utility for engineers. It runs straight from your own server and produces an exhaustive report without sending data to a third party, which matters for closed environments.
How to choose
For a single, maximally detailed scan, pick SSL Labs — its grade has become the de facto industry standard. For ongoing control and alerts you need a service with monitoring: a one-off checker won't warn you when a certificate starts nearing the end of its life. Here enterno.io fits well, tracking uptime, DNS and Ping alongside SSL, with alerts via Telegram, Slack, email and webhook. If you manage many domains from a terminal and don't want data leaving your network, choose testssl.sh. To understand the difference between DV, OV and EV certificates, read our piece on SSL certificate types.
Important: a one-off checker is not a substitute for monitoring. It shows the certificate's state right now, but it won't wake you a week before expiry — for that you need a service with alerts.
FAQ
Can I check an SSL certificate for free?
Yes. SSL Labs, DigiCert, SSL Shopper and the free enterno.io tier all let you run an SSL check online at no cost. Paid features usually cover monitoring, check history and advanced reporting.
What's the difference between an SSL check and monitoring?
A check is a one-time snapshot of the certificate's state right now. Monitoring is continuous tracking with automatic alerts before expiry. Learn more in our article on SSL certificate monitoring.
What does an A+ grade in SSL Labs mean?
A+ means a modern configuration: TLS 1.2/1.3, strong ciphers, a valid chain, no known vulnerabilities and HSTS enabled. A grade below B points to outdated protocols or weak settings worth fixing.
How often should I check a certificate?
Once after each install or renewal. Continuously through monitoring, which will warn you 7–30 days before expiry. Core terms are explained in the SSL glossary.