Open Collective - A new form of association, transparent by design.
Open Collective is an online funding platform for open and transparent communities. We provide the tools to raise money and share your finances in full transparency.
I think this can not be self hosted - correct me if i am wrong.
I think you are right, at least from an initial look at it.
Via the Open Collective slack https://opencollective.slack.com/
This is apparently the place to follow along and support efforts to make Open Collective self-hostable (and generally make it a better tool for communities):
Can I install Open Collective on my own server?
Open Collective is already Open Source (MIT License), so in theory, you already can. But in practice, it's quite difficult. Our goal is to make it much easier.