Depends on your needs. If you need to get something up and running quickly, I would recommend you stick with Ruby. If you can afford some extra time to learn

Depends on your needs. If you need to get something up and running quickly, I would recommend you stick with Ruby. If you can afford some extra time to learn a new framework then both Go or Express/Node.js are great options that would enhance your skill set. Node.js and Go are both growing quickly in popularity. They're much faster on the execution side than Ruby and provide additional optimization opportunities via the ability to query more than one external resource simultaneously and combine the results into your API's response. If you do decide to go with Node.js or Go, Node.js is currently the more popular of the two. You're more likely to be able to land a job or freelancing gig with Node.js skills today, whereas you're more able to contribute something meaningful to the Go ecosystem by getting into it now. Personally I prefer coding in Go, but most of my client's request Node.js.