CBFLIB is a library of ANSI-C functions providing a simple mechanism for accessing Crystallographic Binary Files (CBF files) and Image-supporting CIF (imgCIF) files. The CBFLIB API is loosely based on the CIFPARSE API for mmCIF files. Starting with this release, CBFLIB performs validation checks on reading of a CBF. If a dictionary is provided, values will be validated against dictionary ranges and enumerations. Tags missing under parent-child relationships or category key requirements will be reported. CBFlib provides functions to create, read, modify and write CBF binary data files and imgCIF ASCII data files.