# Free TLS Checker

> Check public TLS and HTTPS evidence for a domain, including certificate health and observable protocol behavior.

Canonical: https://sentryxmonitor.com/tools/tls-checker/
Last updated: 2026-08-08

Free read-only checker

A TLS checker connects to a public endpoint to inspect whether TLS negotiation succeeds and whether the served certificate is valid for the requested hostname and time.

Only check domains you own or are authorized to assess. The scan is read-only and does not exploit systems.

## What is the difference between TLS and SSL?

TLS is the modern protocol. SSL is obsolete, but the term SSL certificate remains common shorthand for a certificate used with TLS and HTTPS.

## What can break a TLS handshake?

Version mismatch, unsupported algorithms, missing key shares, certificate problems, SNI routing, middleboxes, and network failures can all prevent completion.

## What should be monitored continuously?

Monitor endpoint reachability, certificate expiry, hostname coverage, chain behavior, protocol support, and deployment consistency across regions.

## What happens after you submit?

The focused checker opens the full Sentryx outside-in report for the submitted domain. The same public scan backend can show related DNS, TLS, host, email-security, and header evidence so a narrow check can lead to a more complete ownership and monitoring decision.

## Continue learning

- [TLS and SSL Certificate Security Guide](https://sentryxmonitor.com/learn/tls/) - Learn TLS handshakes, certificate chains, hostname validation, expiration, transparency, wildcard and self-signed certificates, and HTTPS outage prevention.

- [What Happens During a TLS Handshake?](https://sentryxmonitor.com/learn/networking/tls-handshake/) - Follow the TLS handshake from ClientHello through certificate validation and encrypted application traffic.

- [SSL Certificate Monitoring](https://sentryxmonitor.com/services/ssl-certificate-monitoring/) - Monitor TLS certificates continuously.

## Related
- [Home](https://sentryxmonitor.com/)