Faerie (name still pending) is the successor to old Super Mario World hacking utilities such as Tweaker and the CFG Editor. It's written in a relatively modular way which allows for future expansion.
The primary goal of Faerie (name still pending) is to edit sprite configuration files for GIEPY. It will also be usable to directly edit a Super Mario World ROM image, which is Tweaker's purpose.
Currently, Faerie (name still pending) is in very early development and it's barely functional.
Faerie (name still pending) is developed through IntelliJ IDEA (currently 2018.1 Community Edition) and built with Maven. Check the .idea directory and the pom.xml file in the repository if you are interested in contributing.