Metakit is an efficient embedded database library with a small footprint. It fills the gap between flat-file, relational, object-oriented, and tree-structured databases, supporting relational joins, serialization, nested structures, and instant schema evolution. There is a C++ API, a Python binding called Mk4py, and a Tcl binding called Mk4tcl (with an optional OO binding on top called Oomk). You can manipulate and exchange data between any of these.

Data files are portable. The library has been used on Unix, Windows, Macintosh, VMS, and others, spanning a range of 16- to 64-bit architectures, from PDA's to S390's.

This library is in active use in various commercial projects and products on millions of desktops.