As a web developer, I hadn’t decided to focus on front-end work until another developer told me about Firebug.
When I started targeting mobile, I switched to the Developer Tools suite (DevTools) built in to Google’s Chrome browser.
Two years later and I’m just beginning to realize what I’ve been missing. I was on the /r/javascript forum on Reddit and the top post is a slide deck showing forty pro tools and tips I had no clue about.
I find DevTools an indispensable utility and yet I’ve only been using 10% of its capabilities.