With these tools you can see exactly how your code affects the browser. At runtime you can find errors in code you’ve written or how long your site takes to load. You can view or even rewrite your CSS rules to see what changes will look like before you ever even commit them to your source files.
You can also dig into the browser itself and inspect its cookies, local storage and cache. And with web users quickly transitioning to mobile devices, developer tool device emulation can show what your site looks like on, and how it will interact with, phones and tablets.
Every year that passes gives us better developer tools from the major browser makers. We are fast coming to a point where any tool you choose will be just as good as another. But for one reason or another developers tend to find themselves gravitating towards a particular set of tools.
When I surf the web I like to use more privacy oriented browsers like, well, anything but Google’s Chrome. But when it comes to debugging and developing code, Chrome takes first place in my world. I like the default look of the Chrome tools UI (although Mozilla’s Dark theme is slightly more pleasant to look at if you’re into dark themes). I also find Firefox developer tools to be a little slow when emulating mobile devices while Chrome is snappier. Other tools in Chrome also appear more polished and have more functionality.
Some browser developer tools might have features that others don’t but that’s usually only true until the others release their next version. Good ideas tend to spread themselves around quickly.