When comparing Lean FT vs Firefox Developer Tools, the Slant community recommends Firefox Developer Tools for most people. In the question“What are the best test automation tools for web apps?” Firefox Developer Tools is ranked 8th while Lean FT is ranked 20th. The most important reason people chose Firefox Developer Tools is:
Particularly strong with inspecting the new CSS Grid layouts.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro It helps move testing closer to the development cycle
It's very easy to go between UFT and LeanFT. Whoever is used with UFT can easily become very productive with LeanFT too, but with the added benefit of moving the testing closer to the development cycle.
Pro Page inspector
Particularly strong with inspecting the new CSS Grid layouts.
Pro Effective for identifying CSS styles in use on an element and testing different styles
Identifying the font in use is one thing Firefox's Developer Tools panel does particularly well, and which Chrome's Developer Tools panel doesn't do.
Pro Debugger
Debugger is useful and informative.
Cons
Con May have some stability issues
Since it's still a (relatively) new product, it may very well have some stability issues, which are sure to be fixed in the future though.