I agree with the last comment, and Mirth has been discussed here. It is portable, lean and “agile”, customizable, not guaranteed of much else. I work with Mirth as both feed from an external EHR, and destination for a portable app. Up to you to master api’s/scripting and create your own magic. If you’re not shy with Java, for example, and want to try portable app. dev to, Mirth can be useful, even fun. It is “free”, in terms of $, but not in terms of your potential efforts required. Design Uncertainty is generally higher, for obvious reasons.
Cloverleaf has all the magic built in, plus lots of customization capability. I think among the best in my experience. Stability and reliability (if configured well) are main benefits. Must admit I used Cloverleaf as the backend to a Mirth engine, feeding a FileMaker portable app.. So, there you go 🙂