How to execute a long process in WEB application?

I have a WEB app (Django/Python/JS) that creates a process which takes 20 minutes. This process can't be done faster. Obviously, it is not good to keep a user waiting for 20 minutes on the same WEB page.

What is the better way to run this 20 min long process? Do I need a forever running daemon or maybe a cron job or something else?