Crystallographic Information File (CIF) is a standard text file format for representing crystallographic information, promulgated by the International Union of Crystallography (IUCr).

The file format was initially published by Hall, Allen, and Brown[1] and has since been revised, most recently versions 1.1 and 2.0.

Many computer programs for molecular viewing are compatible with this format, including Jmol.

Closely related is mmCIF, macromolecular CIF,[3] which is intended as an successor to the Protein Data Bank (PDB) format.

[4][5] Also closely related is Crystallographic Information Framework, a broader system of exchange protocols based on data dictionaries and relational rules expressible in different machine-readable manifestations, including, but not restricted to, Crystallographic Information File and XML.