Operating system

Android from 3.2 (Honeycomb, API-Level 13)

An iOS version will be available soon.
Windows Phone is currently not supported and will not be supported in the future.

Sensors & services

For step detection, an acceleration and compass sensor is required. These are installed in almost all smartphones.
Very few models do not have a compass sensor. The step recognition is nevertheless possible, but inaccurate.
For car detection, either the Google Play-services or a GPS sensor are required.