The Firebug web development tool, an open source add-on to the Firefox browser, is being discontinued after 12 years, replaced by Firefox Developer Tools.
The goal is to make debugging native to Firefox. “Sometimes, it’s better to start from scratch, which is especially true for software development,” Odvarko said. To try Firefox Developer Tools, you can download Firefox Quantum: Developer Edition or update to the current Firefox browser. Mozilla provides guidance on migrating from Firebug to Firefox Developer Tools.