XDF is a general-purpose container format for multi-channel time series data with extensive associated meta information. XDF is tailored towards biosignal data such as EEG, EMG, EOG, ECG, GSR, MEG, but it can also handle data with high sampling rate (like audio) or data with a high number of channels (like fMRI or raw video). Meta information is stored as XML.

XDF is open source and designed to be a community project; that is, everyone is invited to contribute to the format specification. The core specification of the format is kept as simple as possible, but at the same time rich enough to support features such as time stamp corrections, boundary chunks for seeking, and data streams supporting many different data types (including int, float, double, and string).

The XDF concept and beta version was developed by Christian Kothe and Clemens Brunner at the Swartz Center for Computational Neuroscience (SCCN) at the University of California San Diego, CA, USA.