Tomboy is free and open-source desktop note-taking software written for Microsoft Windows, macOS, Linux, and BSD operating systems.

Its interface is a word processor with a wiki-like linking system to connect notes together.

For example, repeated references to favorite artists would be automatically highlighted in notes containing their names.

As of version 1.6 (2010), it supports text entries and hyperlinks to the World Wide Web, but not graphic image linking or embedding.

Starting in 2017 the development team rewrote the software from scratch, for ease of maintenance and installation, renaming it tomboy-ng.