I heard that Chip Mixer doesn't charge you a fee, just whatever you want to donate. I would recommend everyone not to donate anything only if they are really broke. Firstly out of honesty, and secondly because otherwise, if everyone did the same, the business would eventually have to close down.

But looking at the years the mixer has been running well and advertising on the forum, I think there are enough generous people to keep the business going and make a profit.