Angry IP Scanner
This is the source code of Angry IP Scanner, licensed with GPL v2. Official site
The code is written mostly in Java (currently, source level 1.8).
IntelliJ IDEA is recommended for coding (Community Edition is fine).
Projects supports building for Linux, Windows and Mac OS X.
Building 
Use Gradle for building a package for your desired platform:
./gradlew or make in the project dir for the list of available targets.
./gradlew current would build the app for your current platform
The resulting binaries will be put into the build/libs directory.
Run jar files with java -jar <jar-file>.
Deb and rpm packages can only be built on Linux (tested on Ubuntu).
Building of Windows installer can be done on Linux as well.
./gradlew all will build packages for all OS (tested on Ubuntu only, see dependencies below).
Dependencies
On Ubuntu install the following packages:
sudo apt install openjdk-11-jdk rpm fakeroot wine-stable
Note: wine is needed for building of Windows installer.
Install OpenJDK on other platforms as you usually do it.