It's been a while since I ran a receiver, but back when I did ADSBExchange was pretty popular. It looks like there are a number of other options at the moment though - like ADSB.lol and airplanes.live
And anecdotally they now censor some things, as I'm seeing much less private jet and helicopter activity than I used to, especially those that have to be triangulated.
That project is now commercial, but it still shows flights and aircraft that many of the other commercial ones do not. I agree though, supporting the non-commercial ones is important too. I should update my own feeder to do more.
They say they'll give you a free premium membership in exchange for this, which I feel like is a fair deal for enthusiasts like myself. That said, see the recommendation from @mwambua elsewhere in this thread that refers to sharing with other, more open platforms!
It's been a while since I ran a receiver, but back when I did ADSBExchange was pretty popular. It looks like there are a number of other options at the moment though - like ADSB.lol and airplanes.live