Web browsers include "developer tools" to assist with creating and troubleshooting web content.  These tools are free but are not visible by default.

To enable developer tools from a browser's menu options follow instructions below.

  • Firefox: Menu  Web Developer ➤ Toggle Tools, or Tools ➤ Web Developer ➤ Toggle Tools
  • Chrome: More tools ➤ Developer tools
  • Safari: Develop ➤ Show Web Inspector. If you can't see the Develop menu, go to Safari ➤ Preferences ➤ Advanced, and check the Show Develop menu in menu bar checkbox. 
  • Opera: Developer ➤ Developer tools

When the developer tools appear (under a menu bar at the bottom of the web page), click the “Toggle device toolbar” icon to the left of Chrome’s Developer Tools Menu:


or “Responsive Design Mode” to the right of Firefox’s Web Developer Tools menu:


A responsive site will be readable without the need to swipe left and right:


A non-responsive site will have very small text, and/or will require you to swipe left and right as well as up and down to view content: