Tilesetter is described as 'Tileset generator & map editor tool - Create your whole tileset instantly. Generate complete tilesets from base images. Build and export levels directly to Unity, Godot and GameMaker Studio 2' and is an app in the photos & graphics category. There are more than 25 alternatives to Tilesetter for a variety of platforms, including Windows, Mac, Linux, Web-based and iPad apps. The best Tilesetter alternative is Pixelorama, which is both free and Open Source. Other great apps like Tilesetter are Aseprite, LibreSprite, Tilf and GraphicsGale.
Streamline, very easy to use with a stylus on mobile devices anywhere and save to phone.