z88dk is a z80 C cross compiler supplied with an assembler/linker and a set of libraries implementing the C standard library for a number of different z80 based machines. The name z88dk originates from the time when the project was founded and targetted only the Cambridge z88 portable.

The compiler featured in z88dk is a much enhanced Small C compiler; the compiler accepts many features of ANSI C and is only deficient in a few areas where implementation on a z80 processor might prove inefficient. The compiler performs simple optimisations, but the bulk of the optimisation is achieved by a set of peep-hole rules, which will typically reduce the size of a large project by up to a third.