Beyond Tabletop
Roll20
Astral Tabletop
Fantasy Grounds
MapTool
D&D Beyond
PlanarAlly
Rolisteam
Tilesetter
Sprite Fusion
Aseprite
Tiled Map Editor
LibreSprite
Jpixel
Piskel
Zixel
Beyond TabletopWhile many of us have become pampered by DND Beyond's rulebook integration, Beyond Tabletop brings us back to our basics. By removing the integrated rulebooks they allow for every feature to be homebrewed and managed how you and your DM desire. In my findings it is the best tool out there as far as capturing the feel of pen and paper while also giving the versatility and ease of access of the internet.
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.
Fantasy Grounds - Fantasy Grounds is a virtual tabletop to help facilitate play of tabletop-style role-playing games...
Tiled Map Editor - Tiled is a general purpose tile map editor.