HQX files are used by Apple operating systems. HQX is an archive created from an 8-bit binary file. The output format is 7-bit ASCII. This solution made it possible to send data, e.g. by e-mail, as text files. It also gave more confidence that the data would not be damaged when exchanging it between systems.

The BinHex 4.0 tool is used to handle HQX files. HQX are files that take up more memory space than their original counterparts. The header of each file of this type states that it can only be handled by BinHex 4.0.