SSL Certificate Checker
Verify the SSL/TLS certificate of any domain: issuer, validity dates, days remaining, SANs, protocol and grade A+→F. No sign-up.
Built by
Miguel Ángel Colorado Marin (MACM)
Built by
Miguel Ángel Colorado Marin (MACM)
Full-Stack Developer · Guadalajara, España
I develop web apps, digital tools and full projects — from design to deployment.
How to use the SSL checker?
- 1
Enter the domain
Type the domain whose SSL you want to verify (e.g. example.com). Without https:// or paths.
- 2
Click Analyze
The tool establishes a real TLS connection to the server and reads the certificate directly.
- 3
Review the grade
In Infrastructure you'll see the grade A+→F based on days remaining. A+ = >90 days, A = 31-90, B = 15-30, C = 8-14, D = 1-7, F = expired.
- 4
Check the details
Verify issuer, SANs (covered domains), TLS protocol and exact validity dates.
SSL grades and their meaning
> 90 days
Certificate in perfect condition. Renewal not urgent.
31 – 90 days
Valid certificate. Plan renewal soon.
15 – 30 days
Renewal recommended in the coming days.
8 – 14 days
Urgent renewal — less than two weeks.
1 – 7 days
Critical renewal — expires this week.
Expired / Untrusted
Certificate has expired or is self-signed. Browsers show an error.
Frequently asked questions
What is an SSL/TLS certificate?
An SSL/TLS certificate authenticates a website's identity and encrypts communication. Without it the browser shows 'Not secure' and Google penalizes rankings. The correct term is TLS, though SSL is still most commonly used by tradition.
How is the grade calculated?
A+ = >90 days and trusted certificate. A = 31-90 days. B = 15-30. C = 8-14. D = 1-7. F = expired or untrusted. A low grade means urgent renewal.
What are SANs?
SAN (Subject Alternative Name) lists all domains covered by the certificate. A wildcard (*.example.com) covers all subdomains. Modern certificates always include SANs.
What is the difference between TLSv1.2 and TLSv1.3?
TLS 1.3 is more modern and secure: removes weak algorithms, reduces latency and is more resistant to attacks. TLS 1.0 and 1.1 are obsolete and rejected by modern browsers.
Why does Let's Encrypt appear as issuer?
Let's Encrypt is a free CA from the Internet Security Research Group. It issues free 90-day DV certificates with automatic renewal via ACME. It's the world's most used CA.
Is it legal to check any domain's SSL?
Yes. Verifying an SSL certificate is exactly what your browser does every time you visit an HTTPS site — it establishes a TLS connection and validates the certificate. Tools like Qualys SSL Labs, Digicert SSL Checker or any browser do the same thing. We don't access any private content or perform any action beyond reading the public certificate.
Embed this tool
Integrate the SSL Checker in your blog or website:
<iframe src="https://miguelacm.es/embed/ssl-checker" width="100%" height="700" style="border:none;border-radius:12px;" loading="lazy"></iframe>
Source code available on GitHub.
View on GitHub