Populate question options from external source (database or API) using AJAX?

In the KoboToolbox Form Builder, is it possible to populate question options using AJAX or another tool to fetch external data? We would like to add the ability to look up existing users to fetch an unique user ID very similar to what is described here: http://support.kobotoolbox.org/en/articles/978826-pull-data-functionality-in-kobotoolbox, except the data is changing constantly, so it’s impossible for us to upload a CSV file one time.

Is there an alternate to using pull data() functionality that is real time using AJAX or some API call?