DroidWall is described as '- Android Firewall is a front-end application for the powerful iptables Linux firewall. It allows you to restrict which applications are permitted to access your data networks (2G/3G and/or Wi-Fi)' and is an app in the Security & Privacy category. There are more than 10 alternatives to DroidWall for a variety of platforms, including Windows, Android, Android Tablet, Tor and Orbot. The best alternative is AFWall+, which is both free and Open Source. Other great apps like DroidWall are NetGuard (Freemium, Open Source), ZoneAlarm Firewall (Freemium), PC Tools Firewall Plus (Free) and Filseclab Personal Firewall (Free).
A simple fast firewall. No root required. Prevent apps from accessing the internet, save your data, increase privacy, and improve battery life. Does that flashlight app really need internet access? No, Blok it.