Working servers list:
https://hunterskeet.github.io/servers.html
L4d2 player stats:
Global stats:
https://hunterskeet.github.io/global.html
USA stats:
https://hunterskeet.github.io/usa.html
Programs used: NodeJS
Packages:
steam-user (query master server)
steam-webapi (query steam current player count.)
jsonfile (save to json files)
Graphs:
https://apexcharts.com/javascript-chart-demos/area-charts/spline/