The Partner API is an extension to the general public API, which allows to fetch additional resources and gain more control over user data. It uses the same general patterns, technologies and access control (same OAuth tokens) as the whole public Fitbit API.
Access to the Partner API is currently granted on the case-by-case basis. Applications must demonstrate how some of these features are necessary to create a great user experience.
Fitbit is very supportive of non-profit research and personal projects. Commercial applications require additional review and are subject to additional requirements. To request access, email api at fitbit dot com.
Please note: Only select applications are granted access to the Partner API and Fitbit reserves the right to limit this access.
Researchers may be interested in Fitabase, a third-party product that makes using Fitbit devices in research projects easier and provides access to intraday data.
Partner API allows to fetch the intraday data points with 1 minute detail level for several user resources (currently from the activities collection).