EpicTable
Roll20
PlanarAlly
Astral Tabletop
Fantasy Grounds
Beyond Tabletop
Dungeon Scrawl
Dungeon Map Doodler
Fractal Mapper
PyMapper
Campaign Cartographer
Dungeon Tile Mapper
Tiamat
Inkarnate
donjon.bin.sh
Dungeon Builder
Roll20 - Roll20 is a suite of easy-to-use digital tools that expand pen-and-paper gameplay.
PyMapper - Drag and drop tile based mapping program.
PlanarAlly - PlanarAlly is a web tool that adds virtual battlemaps with various extras to your D&D toolbox.
Campaign Cartographer - Campaign Cartographer is the leading map making software for games (RPGs, miniatures and wargaming).
Astral Tabletop - Create, host, and manage your tabletop role-playing games — online or in person
Dungeon Tile Mapper - Dungeon Tile Mapper is a web based tile mapping tool that includes many official D&D tile sets.