Ask HN: What's Your (non-AWS) API Gateway Solution?

I recently started looking for an API Gateway that I could deploy in front of our various RESTful services in order to centralize authentication, access logging, metrics, versioning, and throttling. I won't pretend that we have a microservice architecture, we do have a bunch of services written in various languages, and I thought it would be a good idea to implement something like this in order to normalize them, even if it means a slight performance hit.

I was surprised that this isn't a topic that's really been discussed on HN. So far I've looked at Tyk, Kong, Zuul, Gravitee.io, and Apiman. Here's what I found:

- Tyk and Kong seem promising but their free versions are fairly hobbled, and I work for a non-profit without any real software budget.

- Kong has some interesting community tools, but they don't seem very mature yet.

- Zuul seems like more of a library than a service, and looks like it might require you to buy into the entire Netflix stack to get real benefit from it.

- Gravitee.io looked nice, but it seems like a very small operation, and it's hard to know if it has any staying power.

- Apiman does most of what I need, but it's in maintenance mode, due to Redhat pivoting towards 3scale (a commercial solution, that again, I can't pay for.)

Right now I'm leaning towards using Apiman, and maybe forking it if the official repo becomes too slow. But I'd love to hear others' thoughts or experiences on deploying an API Gateway. Are there other options I haven't considered? Is this even a pattern that people are using in the wild? Has anyone tried it and decided it caused more problems then it solved?