Ask HN: Are there websites that use the Pay What You Like model?

Hi, are there any SaaS / websites that have a Pay as you feel model for pricing? I'm running a free service and want to implement some kind of sustainability if not income. Donation links generally don't work, Patreon seems good but is more about the person, rather than the service. Crowdfunding works but is about short term goals and rewards. I'm not thinking of making my service freemium - all users would have the same features. Perhaps donors could have more space for data and a badge. To me, a pay as you feel model would mean that each user would have to consciously specify some kind of value, even if it's zero, to use the system. I'm also keen on mandating that users should be able to pay nothing to use it. So I'm wondering if there are other sites out there that run a kind of Pay As You Feel, even zero model? Does it work and how?