Why outsource when you can DO IT YORSELF?
Use our interactivity builder to give wings to your on paper exercises. The brilliant UI makes it oh so simple to create interactivities. Just pick the type of interactivity you want to build, plug in content, use the already present several designs or use your own and click export.
You get an HTML5 output that can be run on a stand-alone basis or be consumed by your interactive epub. Below are some of the many types of interactivities you can build. You could also TRY building one right now.