SSL Certificate Checker — Validity, Expiry & Chain

Free SSL certificate checker that connects to any website and reads its HTTPS certificate for you. See whether it is valid and trusted, when it expires, who issued it, which domains it covers, whether the chain is complete, and which TLS versions the server accepts — each result explained in plain language so you know exactly what to fix.

How to Use

1
Enter a domain

Type or paste any domain (e.g. example.com). The https:// prefix and path are stripped automatically.

2
Click Check

We connect to the site over HTTPS and read its certificate, chain and supported TLS versions.

3
Read the verdict

See at a glance whether it is valid and trusted, and how many days until it expires.

4
Fix the warnings

Open the “What this means” section for a plain-language explanation and fix for each issue found.

Inspect a site’s HTTPS certificate and TLS setup in seconds

Connecting and reading the certificate…

Key Features

Validity & Expiry at a Glance
Big, colour-coded days-until-expiry plus the exact valid-from and valid-until dates, with 30/7-day renewal warnings.
Plain-Language Explanations
Every issue — expired, self-signed, name mismatch, missing intermediate — comes with what it means and how to fix it.
Full Chain & Issuer
See the issuing authority and the leaf → intermediate → root chain, and get a flag when an intermediate is missing.
Modern TLS Check
Confirms the server supports TLS 1.2 and TLS 1.3, the protocol versions modern browsers require.
Hostname Match Check
Confirms the certificate actually covers the domain you entered, including wildcard and SAN names.
Regional Reachability
Tells you the vantage point of the check, so you can tell a certificate problem apart from a regional block.

FAQ

What does an SSL checker do?

It connects to a website over HTTPS and reads the TLS/SSL certificate the server presents, then reports whether it is valid, who issued it, when it expires and whether the configuration is secure.

Why does the check run on a server, not in my browser?

Browsers validate certificates internally but never expose another site’s certificate to page scripts, and cross-origin requests are blocked. Reading a certificate therefore has to be done from a server.

My certificate is valid but the tool says the chain is incomplete. Why?

Your server is sending the site certificate without its intermediate certificate. Some browsers fill the gap automatically, but many apps and older devices do not. Install the full chain (often fullchain.pem) to fix it.

It says “unreachable” but the site opens for me. Why?

The check runs from our server’s location. A site can be reachable from your network yet blocked or down from ours. The result notes the vantage point so you can tell a certificate issue apart from a regional block.

How often is the result updated?

Results are cached for about 15 minutes per domain, so repeated checks are instant. A genuinely new certificate will appear after the cache expires.

How do you rate this tool?

Thank you for your rating!
Want to share more? Leave a comment!
Thank you! Your comment will appear after moderation.
Who is this tool for?
💻 Developers & IT Pros 🔒 Security & Privacy
Published Authors: