Because the browser was just an example, this tool handles a lot of different softwares. Sometimes it can even be software you deleted that left cache behind.

I trust this tool as it has been around for a very long time, is well known and open source. But I haven't used it in years as drive space is now cheap so I'm not trying to reclaim every last but of it. It can still be useful in some situations but no need to use it regularly.