SpriteIlluminator is described as 'lets you easily generate normal maps for your 2d game and web projects. Render dynamic lighting & other effects and use paint tools to directly draw on the normal map and fine tune the effects' and is an app. There are more than 10 alternatives to SpriteIlluminator for Windows, Linux, Mac and Python. The best alternative is Laigter, which is both free and Open Source. Other great apps like SpriteIlluminator are Quixel Suite, AwesomeBump, NVIDIA Melody and Crazybump.
Sprite Bump is an advanced 2D Normal Map Generation Tool. It takes in a single 2D image and generates a normal map and optional ambient occlusion map for use in 3D Lighting for realtime Game Engines ( Unreal Engine, Unity etc.