Diagnosing Security Issues with Google Chrome’s DevTools

Google Dev Tools

Welcome to part 2 of our 3 part series on delving into some of the most useful features and functions of Google Chrome’s DevTools. In part 1, we went over a brief introduction of DevTools, plus some minor customisations. In this part 2, we’ll be taking a look into the security panel section of DevTools, including some of the different things you can look at when diagnosing a website or application for security and SSL issues.

The Security Panel

One of Chrome’s most helpful features has to be the security panel. To begin, visit any website through Google Chrome and open up DevTools, then select “Security” from the list of tabs at the top. If you can’t see it, you may need to click the two arrows to display more options or increase the width of DevTools.

Inspecting Your SSL Certificate

When we talk about security on websites, one of the first things that we usually would consider is the presence of an SSL certificate. The security tab allows us to inspect the website’s SSL certificate, which can have many practical uses. For example, when you visit your website, you may see a concerning red “Unsafe” warning. If you suspect that that may be something to do with your SSL certificate, it’s very likely that you’re correct. The problem is, the issue with your SSL certificate could be any number of things. It may be expired, revoked, or maybe no SSL certificate exists at all. This is where DevTools can come in handy. With the Security tab open, go ahead and click “View certificate” to inspect your SSL certificate. In doing so, you will be able to see what domain the SSL has been issued to, what certificate authority it was issued by, and its expiration date – among various other details, such as viewing the full certification path.

For insecure or SSL warnings, viewing your SSL certificate is the perfect first step in the troubleshooting process.

Diagnosing Mixed Content

Sometimes your website may show as insecure, and not have a green padlock in your address bar. You may have checked your SSL certificate is valid using the method above, and everything is all well and good there, but your site is still not displaying a padlock. This can be due to what’s called mixed content. Put simply; mixed content means that your website itself is configured to load over HTTPS://, but some resources (scripts, images, etc) on your website are set to HTTP://. For a website to show as fully secure, all resources must be served over HTTPS://, and your website’s URL must also be configured to load as HTTPS://.

Any resources that are not loading securely are vulnerable to man-in-the-middle attacks, whereby a malicious actor can intercept data sent through your website, potentially leaking private information. This is doubly important for eCommerce sites or any sites handling personal information, and why it’s so important to ensure that your website is fully secure, not to mention increasing users’ trust in your website.

To assist in diagnosing mixed content, head back into the security tab again. Once you have that open, go ahead and refresh the website that you’re diagnosing. If there are any non-secure resources on the page, the panel on the left-hand side will list them. Secure resources will be green, and those non-secure will be red. Oftentimes this can be one or two images with an HTTP:// URL. Whatever the case, this is one of the easiest ways to diagnose what’s preventing your site from gaining a green padlock. Once you have a list of which content is insecure, you can go ahead and manually adjust those issues on your website.

There are always sites like “Why No Padlock?” that effectively do the same thing as the steps listed above, but the beauty of DevTools is that it is one tool that can do it all for you, without having to leave your website.


This concludes part 2 of our 3-part DevTools series! As always, be sure to head over to Google’s Chrome DevTools documentation for further information on everything discussed here.

We hope that this has helped you gain some insight into how you might practically use DevTools when troubleshooting security and SSL issues on your own site. Now that you’re familiar with the basics of the security panel stay tuned for part 3 where we will get stuck into some of the most useful DevTools tips and tricks of all.