For being so progressive, I'm surprised that not a single listing I clicked had salary ranges.
It's just not worth the effort of even considering these companies without salary ranges. 4-day work weeks mean nothing if it means getting paid <80% market rate.
I'd do four 10-hour days. if that's what it takes.
But it's not worth the effort and time to research dozens of companies if they're all going to tell me that I'd need to take a significant pay cut. And if a listing on that site doesn't have the salary range, that's what I'm going to assume is going to happen.
It's just not worth the effort of even considering these companies without salary ranges. 4-day work weeks mean nothing if it means getting paid <80% market rate.