So, I'm visiting a random site, and Chrome reports it as "not secure," even though it's using https with a valid certificate. Just as a matter of self-education, I want to understand what they're doing wrong. What things do I need to read about? What kind of tools should I learn how to use.

This is Stack Exchange, so you should make your answer as general as you can.

  • Questions here are required to be about a website under your own control. Additionally, this is really too broad since there could be many potential issues that result in this. The answer below however is one of the more common reasons we see here.
    – dan
    Commented Sep 25, 2018 at 2:34
  • Chrome is certainly telling you more than just "not secure" .... Commented Sep 25, 2018 at 14:42
  • I think the "site not under your control" rule doesn't apply, since the question isn't about the site. But if you consider this too broad a question, by all means close it. Commented Sep 25, 2018 at 20:03

1 Answer 1


I'm using Chrome so, when I click the SSL certificate information button, I see the following:

Your connection to this site is not fully secure

This indicates that the site is serving some contents over a TLS connection, but other contents are being served over HTTP (unencrypted).

There's nothing wrong with this site's SSL certificate (at least, not anything conspicuous) but, when you encounter a certificate warning like a "This site is not safe" browser warning, you can diagnose the issue with Qualsys' SSL Checker (or another online SSL checker of your choosing - Google "ssl certificate analysis" for a handful of options).

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