Editors

Booster's Lab
by Noxid

An actively updated in-development editor written in Java. It can be used to create both CS and CS+ mods. Booster's Lab v0.4.2.0 (Dawn of April Edition) Booster's Lab v0.4.1.4 (English) Booster's Lab v0.3.3.0 (Japanese) Forum Thread  

Cave Editor
by Wistil

Has a number of features not present in Booster's Lab. Both editors are compatible with each other so it's down to personal preference as to which interface you prefer. Cave Editor v0.99d Source Code Forum Thread  

Ikachan Map Editor
by gamemanj

A map and npc editor for Ikachan. Ikachan Map Editor v15.2 Ikachan Map Editor v13.1 Forum Thread  

Kero Hack Tools
by JMickle

A map editor for Kero Blaster and Pink Hour. It isn't all that user friendly so check out the usage instructions link below before you use it. KeroHackTools v1.2 Usage instructions Forum Thread