QField is built on top of the professional QGIS open source project, allowing users to setup maps and forms in QGIS on their worksation, and deploy those in the field through QField.
Leveraging QGIS' data providers - OGR, GDAL, PostGIS, and more - QField supports a wide variety of vector and raster formats.
Datasets can be locally stored or accessed remotely.
QField gives the users full control by allowing projects to be synchronized via USB cable as through the Internet via WiFi, a mobile network connection, etc.
QField is released under the GNU Public License (GPL) Version 2 or above. Developing QField under this license means that you can inspect and modify the source code and guarantees that you will always have access to a QGIS based field data collection app that is free of cost and can be freely modified.
You can find the source code on github.
QField is an open source project. It is free to share, use and modify and it will stay like that. We are very happy if this app helps you in whatever creative way you may use it. If you found it useful, we will be even happier if you could give something back. A couple of things you can do are:
QField is developped by OPENGIS.ch. OPENGIS.ch does consulting, development and training for open source software including QField and QGIS.