Pocver is described as 'contains a rich collection of unit conversion tools and it's simple to use and minimalist, currently has 6 conversion tools that are mostly used in daily life and we aim to continually expand the tools set base on user demands' and is an app in the Office & Productivity category. There are more than 10 alternatives to Pocver for a variety of platforms, including Android, Windows Phone, F-Droid, iPhone and Android Tablet. The best alternative is Unit Converter Ultimate, which is both free and Open Source. Other great apps like Pocver are Material Unit Converter (Free), unitMeasure (Paid), multiConvert (Free, Open Source) and ConvertPad (Free).
With over a hundred measurements, and fifteen categories, you won't need to search the internet or fiddle around looking for answers anymore. This is a completely offline solution, with no permissions whatsoever.