The Kimwitu system is a meta-tool that supports the construction of programs (tools) that operate on trees or terms. The system supports open multi-paradigm programming, in that it allows to express each part of an implementation in the most appropriate language. Terms can be implemented in a tool as well as exchanged between tools. In this way tool integration is facilitated. Experience has demonstrated that Kimwitu drastically speeds up development time, facilitates tool integration and generates production quality programs.