QTMPlay was written with extendability in mind, and hopefully has turned out so. The main player module of QTMPlay, "QTMPlayer", is structured so that if a programmer wants to add his new player module into QTMPlay, it is only a matter of writing a small piece of ARM code, and QTMPlay will instantly treat all the new files as though they were built in QTMPlay. Thus the number of song formats which QTMPlay can use are limitless. A full API and programmer's distribution, including documentation, C-language veneer and debugging tools is available from the QTMPlayer section.
However, this is not the only modular part of QTMPlay. QTMPlay is designed so that a programmer can add features to it by writing small bits of BASIC code. QTMPlay provides a full API, including calls that will handle user preferences for all of these modules via a special set of routines that convert a text description into a window. Examples of plugins include "ToolTips", a plug-in to place an icon for QTMPlay on the iconbar, a plug-in which tells you which song formats QTMPlay can recognise, and a plug-in to popup a window when QTMPlay is loading. Full details are included with QTMPlay as to how to write plugins.