SSL Certificate Checker
Check whether a site serves HTTPS, when its certificate expires, whether browsers will trust it, and how HTTP traffic is redirected.
What this tool checks
- Whether HTTPS is enabled on port 443, or TLS on a port you choose
- Certificate expiry date and days remaining
- Hostname coverage and chain trust, with the reason when it fails
- Whether CAA records still let your certificate authority renew
- TLS versions, including legacy TLS 1.0 and 1.1
- IPv4 and IPv6 reachability, and the same certificate on every address
- HTTP → HTTPS redirect, HSTS and security headers
How to read the results
- Pass
- The check succeeded based on the observed responses.
- Warning
- Works now, but is risky, unusual or worth reviewing.
- Fail
- A problem was observed directly in the responses.
- Inconclusive
- Not enough evidence — for example a server did not respond.
Frequently asked questions
- How do I check when an SSL certificate expires?
- Enter the domain above. The checker shows the expiry date and days remaining for the certificate each server address actually presents, so it also catches a server still serving an old certificate after renewal.
- Why is my SSL certificate not trusted?
- Usually the server is not sending its intermediate certificate, the certificate is self-signed or from a private CA, or it does not cover the hostname. The result says which check failed and how to fix it.
- Does this check the HTTP to HTTPS redirect?
- Yes. It follows the request from http:// step by step, shows each status code, and reads the HSTS header and other security headers.
- Can I check a certificate on a port other than 443?
- Yes. Enter a port to test TLS on another service, such as a mail server on port 465 or 993.