Best API code generator

What kind of APIs are you trying to generate? If you're trying to do more than REST/HTTP APIs, you can check out Quark (https://github.com/datawire/quark).

I've used https://github.com/mulesoft-labs/raml-generator it let's you define your templates in handlebar.

I kinda favor the parsing/runtime concept over codegen. I find codegen hard to maintain.

What are you trying to achieve?

We're developing apiplug.com to solve this problem. We also produce swagger documentation as a side product. Free in beta right now. Supports nodejs & php.