I/O continues to be one of the main bottlenecks for scientific applications at scale. We support two software packages that many application developers use to manage I/O of heterogeneous types of binary application data used on many different platforms. HDF5 and NETCDF are both implemented on top of MPI‐IO and have gained popularity as alternatives to basic POSIX I/O. HDF5 is a machine-independent and self-documenting file format. Each HDF5 file "looks" like a directory tree, with subdirectories, and leaf nodes that contain the actual data. This means that data can be found in a file by referring to its name, rather than its location in the file. NetCDF is a file format and support library developed at the National Center for Atmospheric Research (NCAR). Like HDF5, NetCDF is self-describing and portable across platforms.