Good options for cheaply hosting a simple REST API?

I need to host a very simple REST API. I don't care about the implementation language, could be JS, Ruby, even Go for all I care. I'm looking for recommendations on good hosting providers for this that aren't too expensive. I don't need a full webspace, otherwise I would just rent one, but I was hoping there would be cheaper options for such a simple usecase

Edit: thanks guys, got a lot of suggestions! I'll do some research into them. Super helpful :)