Terraria Tweaker is TiberiumFusion's tool that applies different tweaks/patches to Terraria by injecting itself into the Terraria process without modifying Terraria.exe. It was heavily inspired by TerrariaPatcher.

Unfortunately, due to some drama, TT2 is no longer publicly distributed. However, if you obtain an older version of it, it will be possible to update it with a built-in updater.

Despite all the claims, TT2 is NOT confirmed to be malware.