API Versioning in Rails: Start at /api/v1 Before You Think You Need It

Most Rails APIs start as a format.json branch in an HTML controller and only become an API once a partner depends on them. This post lays out the structure to put in place before that: URL path versioning starting at /api/v1 , an Api::BaseController < ActionController::API that owns auth, error envelopes and transaction tagging, and one thin base per version.