Like many older Android apps, it has a Gingerbread-style interface and isn't all that pleasant to use. We tried Search Duplicate File(Super) - the most popular duplicate-file-finder app in Google Play at the moment - and found it worked fine.
VisiPic works well for hunting down duplicate photos with a nice visual interface. We liked the dupeGuru applications for this, but Duplicate File Finder offers more basic and potentially faster scanning, DigitalVolcano's Duplicate Cleaner Free is decent if you want a commercial application that gives you a prettier interface at the cost of a few nag screens. There are also paid applications that you don't really need to buy because freeware will work just fine for you. There are many different duplicate-file-finder apps that probably work okay, but want to force various toolbars, search engine changes, and other junkware onto your system when you install them. The biggest problem when searching for a duplicate-file-finder for Windows is all the junkware. Related: How to Find and Remove Duplicate Files on Windows
No Chrome apps are currently available to do this on a Chromebook. Apple's iOS doesn't offer a user-visible file system, so you can't do this on an iPhone or iPad. The applications here cover Windows, Mac OS X, Linux, and even Android.
