TLS Checker
Enter a domain to see which TLS versions its server accepts, and which one gets negotiated by default.
Overview
TLS has gone through several protocol versions — TLS 1.0 and 1.1 are deprecated and considered insecure, 1.2 is the current widely-supported baseline, and 1.3 is the modern standard. This tool probes a server with a separate handshake for each version to see which ones it accepts, and reports the version and cipher suite negotiated by a normal connection.
This is a different focus from SSL Checker: SSL Checker reports the certificate itself (issuer, validity, trust), while this tool reports the protocol-level configuration — which matters for compliance requirements (e.g. PCI DSS requiring TLS 1.0/1.1 to be disabled) and for diagnosing why older clients might fail to connect.
Examples
A modern server
example.com
TLSv1.2: supported TLSv1.3: supported
How It Works
- Enter a domain name, e.g. example.com.
- Complete the verification check if shown.
- Click Check to probe the server with a handshake for each TLS version.
- Review which versions are supported and which one is negotiated by default.
Use Cases
Confirming deprecated TLS versions are disabled
Check that TLS 1.0 and 1.1 have actually been turned off after a planned hardening change.
Diagnosing legacy client connection failures
Check whether a server has dropped support for an older TLS version that some older clients still rely on.
Tips
- TLS 1.0 and TLS 1.1 are deprecated by major browsers and most compliance standards — supporting only 1.2 and 1.3 is the current best practice.
- The "negotiated" protocol is whichever version a normal connection settles on, typically the highest one both sides support — it can differ from the full list of versions the server is technically willing to accept.
FAQ
SSL Checker reports the certificate itself (issuer, validity, trust). This tool reports the protocol-level configuration — which TLS versions the server accepts.
This check makes several TLS handshakes to a server you specify, so a quick bot check helps keep the tool available and responsive for everyone.