Geon FX
Simply stunning Particle Editor for GameMaker Studio 1-2 with a PNG and GIF Export
Transmutation Circle Maker
For the alchemist enthusiasts!
Particle Editor
Small particle editor for GameMaker
Fixture Editor for GameMaker: Studio
Make concave shapes!
Simulation Starter Kit (Engine, Editor and SDK)
A plugin-based 3D engine, editor and SDK (C++ / CMake / OpenGL / GLSL / SDL2 / Lua)
GM's Cam-Edit
A Camera Making Editor For Game Maker.
GM Lite
GameMaker Leightweight Code Editor
Particulum Particle Editor
Simple and easy particle editor