A JMS file is a project created by Hot Potatoes, a suite used to create various quizzes, puzzles, and other problems. It stores the settings of each tab of your Masher project, which includes exercise files, appearance, buttons, and index information.

The Masher is used to build different exercises into one cohesive unit in order to be published to a web page. The Masher also adds a navigation bar if necessary and an index.htm file to help users work through the different materials in the correct order. NOTE: In 2009, the software was released as freeware.