I haven't used this site but I did run a service a while ago that had 100K free users. All the talk here about not using AWS is bunk. Not needle moving. OP need

I haven't used this site but I did run a service a while ago that had 100K free users. All the talk here about not using AWS is bunk. Not needle moving. OP needs to bite the bullet and charge their customers. At least some of them, for something. Heck some of their traffic probably comes from bots. Bill them. Make a white label version and try to sell that to big customers. Actually the other way round: try to sell it then make it if they bite.