Data files that contain our pulse profiles as a function of time, polarization, frequency, and phase (search data are also contained within PSRFITS files). These are built on standard FITS (Flexible Image Transport System), which allows for data to be stored in binary formats and metadata, e.g., about the observation, to all be stored internal. The standard package to handle these files is PSRCHIVE, but NANOGrav has an all-Python package called PyPulse which has much of the PSRCHIVE functionality.