What is the best passive income for online workers?

[Kane]

Most of the works you do online are active income source. For instance, if you are a freelancer, you have to work actively. If you are a blogger or vlogger, you have to work actively. However, there are also passive income sources, for instance selling digital items like ebooks, arts, or selling merch. By the way, what do you think is the best passive income source for online workers.