Roll20
Roll20 is a online platform to play RPGs online if you don't have friends or just need the that vidya feeling to your Pen and paper games.
In last quarter of 2017, there where 49,265 active games of Dungeons & Dragons 5th Edition, compared to only 9856 active games of Pathfinder, dwarfing all other systems activity in comparison.[1]
Basics dice rolling exist and you can simulate throwing dice if you are really needy. Macros, API and Dynamic Lightning are some of the features. Many character sheets have scripts and macro rollers to automate and streamline playing, making some RPG systems more playable than plain pen and paper. Most character sheets are created by the community.