KoBoToolbox is a suite of tools for field data collection for use in challenging environments. The software is free and open source. Most users are people working in humanitarian crises, as well as aid professionals and researchers working in developing countries.
CyberTracker supports data collection for KoBoToolbox. This includes downloading forms, data collection and submission. CyberTracker extensions are not visible in the KoBoToolbox form editor. To use them, you must maintain the XlsForm separately and upload it when changes are made.
Check out the tutorial for getting started with KoBoToolbox.