NoRoot Firewall

Just as its name suggests, NoRoot Firewall is a firewall that lets you block any app from accessing the Internet and doesn't require root privileges. Each time one of your apps tries to access the Internet, you'll receive a notification and can choose to allow the connection or deny it.

From one of the tabs in NoRoot Firewall, you can select the applications one by one and decide if you want to allow them to access the Internet. Of course, you can also do this automatically instead of manually by denying or permitting access for multiple apps at once.

One of the strengths of NoRoot Firewall is that it doesn't ask you for any permissions after you install it. Not one. This is drastically different from similar applications in which you are often required to accept certain permissions.

NoRoot Firewall is a great firewall, the highlights being its simple interface and powerful features.