Ask HN: Does a new features payment platform for free and OS software exsist?

Does a platform or service exist for free and open source software to allow for individual and/or crowd sourced payment for the addition of new and enhanced features (and possibly user-backed bug bounties to encourage developers to address specific bugs)?

I have a couple smaller projects I’m getting ready to release, either free or OS, and this is the funding model I’d like to use. I feel like it would be a way to directly balance the time invested in projects with the (serious) interest from end users.

I’ve done a bit of searching, but I’m not able to find such a service, perhaps for lack of knowing what keywords to search on.

Does this exist, or should I be thinking about this as a possible next project? ;)