Free SSL Checker for Any Website
Check if a website’s SSL certificate is valid and trusted, see when it expires, who issued it and which names it covers. Also find subdomains from public certificate logs.
- What it doesChecks an SSL certificate and its expiry
- AccuracyExact, read from the live certificate
- Works withAny public domain on port 443
- PriceFree, no sign-up, no limit
- Last reviewed
What Is an SSL Checker?
An SSL certificate (more correctly a TLS certificate) lets browsers connect to your site over HTTPS, so data is encrypted. When it expires, does not match the domain or is not trusted, browsers show a full-page warning and many visitors leave. Google also uses HTTPS as a light ranking signal. Checking your certificate takes seconds and can save you from a costly outage.
- Shows valid, trusted and name match in one result
- Days left before the certificate expires
- Issuer, covered names, TLS version and chain
- Finds subdomains from public certificate logs
- Free, no sign-up, no limits
How to Use the SSL Certificate Checker
Enter a domain
Run the check
Read the result
Review the details
Find subdomains
Fix common SSL problems
- Expired: renew it, and check that auto-renew is on with your host.
- Name does not match: the certificate must cover both example.com and www.example.com if you use both.
- Not trusted: usually a missing intermediate certificate. Install the full chain.
- Mixed content: a valid certificate can still show warnings if the page loads http:// images or scripts.
SSL Check Results Explained
| Result | What it means | What to do |
|---|---|---|
| Valid and trusted | All good. Browsers trust the certificate. | Make sure auto-renew is on |
| Expiring very soon | Less than 14 days left | Renew now |
| Certificate expired | Browsers show a security warning | Renew and install the new certificate |
| Name does not match | The certificate does not cover this domain | Get a certificate that covers every name you use |
| Not trusted by browsers | Self-signed or missing intermediate chain | Use a trusted CA and install the full chain |
How the SSL Certificate Checker Works
- 01
A secure connection is made
Our server connects to your domain on port 443 and starts a TLS handshake, like a browser.
Our server - 02
The certificate is read
The tool reads the issuer, valid from and to dates, covered names and the chain.
Our server - 03
Trust is checked
The chain is checked against trusted root certificates, and the domain is matched to the covered names.
Our server - 04
Days left are counted
Days left = expiry date minus today. Under 14 days is a warning.
In your browser - 05
Subdomains are found
Public certificate transparency logs (crt.sh) are searched for names on your domain.
Our server
How We Judge a Certificate
- Not expired: today is between the valid from and valid to dates.
- Trusted: the chain leads to a root certificate browsers trust.
- Name match: the domain is in the certificate’s names, including wildcard names like *.example.com.
- Time left: under 14 days shows a warning so you can renew in time.
Is the SSL Certificate Checker Accurate?
- Valid, expired and self-signed certificates give the right result
- Name mismatch is caught, including wildcards
- Days left are counted correctly
- Missing chain problems are found
- Subdomain lookups return results from the logs
Accuracy in plain words
Results are exact for the server we reach. Sites behind a CDN like Cloudflare show the CDN’s certificate, which is what visitors see. The subdomain list only includes names that appeared in public certificate logs.
Features of the SSL Certificate Checker
Valid and trusted
One clear answer for validity, trust and name match.
Expiry countdown
See days left and get a warning under 14 days.
Full details
Issuer, covered names and TLS version.
Chain view
See the full certificate chain up to the root.
Subdomain finder
List subdomains from public certificate logs.
Plain word fixes
Every problem comes with a clear next step.
Limitations of This Tool
- It cannot install or renew a certificate for you
- It does not find mixed content on your pages
- It only checks port 443 on the domain you enter
- The subdomain list only shows names in public logs
- Turn on auto-renew with your host or CA
- Cover both www and non-www names
- Check the HTTPS redirect with our Redirect Checker
- Re-check after moving hosts or CDNs
Who Can Use This SSL Certificate Checker?
Site owners
Avoid "Not secure" warnings and lost sales.
Site admins
Track expiry dates across many domains.
SEO specialists
Confirm HTTPS works before and after a migration.
Careful visitors
Check who a site's certificate was issued to.
Updates, Bug Fixes and Reviews
SSL Certificate Checker launched
First release with validity, trust and name checks, expiry countdown, chain view and subdomain finder.
Full re-test and rules review
We run the tool against our test cases again and check certificate standards and browser trust rules for changes.
Tool page last reviewed on .
Found a bug or a wrong result?
Tell us what you entered, what happened and what you expected. Our developer checks every report, fixes confirmed bugs as a high priority and tests the fix before it goes live.
Who Built and Reviewed This Tool
Hassan
Muhammad Ahtesham
Afza
Sources we follow
Our standards
This page follows our Editorial Policy and Methodology. If something here is wrong, our Corrections Policy explains how we fix it. Learn more about the SpellMistake team.
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SSL Certificate Checker FAQ
What does an SSL checker do?
It tests a website's SSL certificate and tells you if it is valid, trusted, covers the domain and when it expires.
Is this SSL checker free?
Yes. It is 100% free, with no sign-up and no limits.
How do I check when my SSL certificate expires?
Enter your domain and run the check. The result shows the expiry date and the number of days left.
Why does my site say "Not secure" with a valid certificate?
Usually because the page loads some images or scripts over http://. This is called mixed content. Change those links to https://.
What is the difference between SSL and TLS?
TLS is the modern version of SSL. People still say "SSL certificate", but today's connections use TLS 1.2 or TLS 1.3.
Does SSL help SEO?
Yes, a little. Google uses HTTPS as a light ranking signal, and a secure site keeps visitors from leaving because of warnings.
How does the subdomain finder work?
It searches public certificate transparency logs for certificates issued to your domain and lists the names they cover.