SSL/TLS Certificate Checker
Open a live TLS connection to a domain and inspect its certificate, protocol and supported TLS versions.
Result for 0521.biz
Valid
Not trusted
The certificate is not trusted by default (self-signed, hostname mismatch, or incomplete chain): unable to get local issuer certificate. Protocol and cipher are still shown below.
- Issuer
- -
- Subject (CN)
- -
- Valid from
- -
- Valid to
- -
- Negotiated protocol
- TLSv1.2
- Cipher
- ECDHE-RSA-AES256-GCM-SHA384
TLSv1.2
FAQ
Why does it show data even for invalid certificates?
We report the presented certificate regardless of trust so you can diagnose mismatched or self-signed certs.
What are "weak TLS versions"?
TLS 1.0 and 1.1 are deprecated. If the server still accepts them, disable them in your server config.
How soon should I renew?
Renew well before expiry; automated issuers like Let's Encrypt renew ~30 days out.
About SSL/TLS checks
This tool opens a direct TLS connection to the domain on port 443 and reads the certificate the server presents. Nothing is sent to a third party - the check runs entirely on our infrastructure.
- A trusted, unexpired certificate avoids browser warnings and SEO penalties.
- Keep only TLS 1.2 and 1.3 enabled.
- Make sure the certificate's SAN list covers every hostname you serve.