Ask HN: Best alternative to BuyMeACoffee?

I feel like BuyMeACoffee is unnecessarily limiting.

$15 is the max the interface allows if I'm not mistaken, but for some products people may be willing to drop way more than that.

If I had the resources for it, I'd run a psychological study and I just have a feeling depending on the interface people are willing to give more or less, with BMAC perhaps being on the lesser side.

What's an alternative that allows people to give whatever they feel like rather than suggesting them a specific amount?