Esrael Sonic Editor

Esrael Sonic Editor (ESE) is a suite of hacking utilities offered for free by Esrael. There are two versions of this program, ESE (written in Visual Basic) and the superior ESEII (written in Delphi). ESEII adds the ability to import levels from other games in Sonic 2 as well as a few bugfixes and extra features. The program was designed to be in Portugese but can easily be set to other languages, though some dialogs may still appear in Portugese.

It features editors for various levels and bonus stages, a data converter for porting stages between games, an IPS patcher, and an SMD<->BIN converter, among other things. However, it's rather buggy, and hasn't been updated in years. The hacking community now has a much better understanding of the way the games work, and new techniques for ROM editing, but they haven't been applied to ESE. Its main advantages over SonED and SonED2 are the more user-friendly interface and integration with several useful tools.