Roll20 - Roll20 is a suite of easy-to-use digital tools that expand pen-and-paper gameplay.
Sprite Fusion - Design your game with Sprite Fusion, the ultimate free online tilemap editor. Design 2D games with ease, direclty export to Unity Tilemap and Godot Scenes. Ideal for retro games!
Astral Tabletop - Create, host, and manage your tabletop role-playing games — online or in person
Aseprite - Aseprite is an art program dedicated to the creation of pixel art.
D&D Beyond - Official online toolset for Dungeons & Dragons tabletop gaming
LibreSprite - Free and open source program to create animated sprites.