Math Keyboard is a utility tool available for Android users, developed by Fairbird Innovation. This free app offers a unique keyboard layout designed specifically for mathematical input. The keys are categorized into different key-groups, catering to various needs. The Criteri-R key-group is tailored for the Criteri-R app, while the User key-group allows customization of key texts like macros.

In addition to standard math input keys, Math Keyboard features mutable keys that users can customize to map to any keys within the selected key-group. This flexibility enables users to define as many keys as required in the User key-group, making the keyboard versatile for not only Criteri-R but also other applications like Excel and WolframAlpha.