fNIRS is now broadly adopted for measuring human brain function, particularly in ecologically valid settings and in subjects and paradigms not easily studied with fMRI. We have worked with the fNIRS community through the Society for fNIRS and developed the Standard functional Near InfraRed data Format (SNIRF). SNIRF is documented and distributed through the Society for fNIRS github page at github.com/fnirs and is being adopted by companies and academics to facilitate the sharing of data and analysis methods. The goal of our supplement is to establish the the necessary standards for organizing fNIRS data that will facilitate the sharing of data in a format that easily enables results to be verified by others using the same or different processing pipelines. In addition, our effort will enable the user community to easily adopt standardized protocols for quality assurance of their data as well as standardize data processing pipelines.