Inapp Translator is a rather handy utility that, as the name suggests, offers you translation features within any app that allows text to be copied, without leaving that app and switching to a dedicated translation app. But while it offers convenience, the app does have some quirks and limitations that might turn off a few users.
The way Inapp Translator work is technically simple. Once activated, it runs in the background and monitors your device's clipboard, that virtual space where copied text resides. Once text in a supported language is detected, the app will translate the text into another supported language, all configurable, of course. All of these happens in a floating window, ala Facebook Chat Heads, so that you can do everything without having to leave your app or browser. You can tap and hold on the translated text to bring up options to copy it to the clipboard as well. An easy and convenient path, definitely, but getting there has a few bumps in the road.
First, you will have to activate the floating icon via the Inapp Translator app itself, which could cause you to leave the currently running app anyway and negates the whole promise of the translator app. Unless, you don't mind having a floating T enclosed in a circle hanging around your screen all the time, even when you don't need it. Banishing the icon is easy, involving only a tap and hold gesture. Of course, after that, you'll need to activate it again when and if you need it. Translating isn't automatic either. Aside from highlighting the text you want translated, you have to explicitly copy it to the clipboard and then tap on the Inapp Translator floating icon to translate the text. Still, it's better than jumping between apps just to get the right words.
Inapp Translator uses Microsoft Translator for its backend, which might be a bit surprising until you find out that Google Translate's API doesn't have a free, but limited, offering. Inapp Translator itself is free, but offers an in-app purchase option to get rid of ads which, for a limited time only, will only cost 1€.