One of the benefits that rooted users have enjoyed for a while were root firewall applications that allowed us to download horribly permissioned applications and deny them access to send our data to a data mining company somewhere. Now that benefit, at least the firewall aspects thereof, doesn’t require root.
NetGuard is a firewall for Android 5.0+. It’s a no-root way to block the internet from applications you don’t trust, or that use way too much data for their own good.
NetGuard is open source, doesn’t require any strange permissions, works on IPv4, IPv6, TCP/UDP, can block user and system applications, can block by interface (WiFi/Cell,) doesn’t advertise to you, doesn’t phone home, doesn’t ask for money, it’s pretty sweet.
The API it uses was introduced in Android 5.0, so there will be no backporting to KitKat and the older of Android’s snackfoods, but anything released in the past year or two should be able to run it without any issues.
If you’re really paranoid, you can even download the source code and look through it for a gotcha, compile it yourself, and use your own compiled version so you know it’s the same code.
Download: Google Play