Nag is a web-based application built upon the Horde Application Framework which provides a simple, clean interface for managing online task lists (i.e., todo lists). It also includes strong integration with the other Horde applications and allows users to share task lists or enable light-weight project management.

This package is part of Horde, a web application Framework written in PHP with modules like IMP (webmail), Turba (contacts), Kronolith (calendar), Nag (task list), Gollem (file manager), etc.