It feels like this is the quintessential "feature, not product" startup. The goal of these should be either:

A. to acquire a huge customer base and then pivot into satisfying them with a larger "suite" offering which includes your original service as a feature,

or B. to be acquired by another company with a huge customer base... and then integrate your feature into their suite. :)

I could see, for example, Github buying this (and other things like it) and launching a featureful, language-agnostic online IDE that compiles against Travis-CI.