When I started working on porting Firmata to other AVR processors, and eventually to non-AVR chips, all host-side Firmata implementations required complex systems like Puredata, Max/MSP, Open Frameworks, etc.
I created this simple (open source) stand-alone program to easily test Arduino compatible boards running Standard Firmata version 2.2 or higher (using the auto-detection of pin capabilities added in Firmata version 2.2).