From Sonic Retro
SA Tools (formerly known as SADXPCTools) is a collection of tools for editing data in various versions of Sonic Adventure and Sonic Adventure 2. It was first written by MainMemory in C# 2008, and is now actively developed and maintained by several people. The project is currently undergoing a major overhaul, including the 'project manager' update, which cleanly separates the mod and game folders, to allow for working on multiple mod projects at once with a single game install.
Because the project is currently in-flux, and now has its own wiki on GitHub, the latest documentation (project updates, usage instructions, tutorials, etc) can be found at the SA Tools Github Page
The latest version of the tools is always available here: