From their site: Dabble lets you do a lot without ever having to write a line of code — from simple data modeling, to standard CRUD operations (creation, retrieval, update and deletion), importing and exporting data, searching, and back-linking, Dabble handles the common recurring data management tasks for you. Sometimes, though, you need your Dabble application to do something very specific to you or your users. You may have a custom algorithm you want to apply, or you might want to pass your data through a third-party web service. This is where the Dabble Plugin API comes in.
Dabble plugins allow Dabble applications to create new, derived fields by calling out to external HTTP-accessible applications. This solves the problem of safely enabling extension of a centrally-located hosted application, in that, while you’re writing code to extend and enhance the behavior of a Dabble application, your code never actually runs inside Dabble. You might even think of it as a plug out as opposed to a plug in.