GUNDAM was primarily developed as a tool for conducting sensitivity studies with the Upgraded ND280 Detector. Originally, it was created as a fork of the xsllhFitter project, which was developed and used by the T2K cross-section Working Group. The original project is available on GitLab. GUNDAM also benefits from over 10 years of expertise gained by the T2K Oscillation Analysis Working Group through the near-detector analysis part of the T2K oscillation analysis, which uses the internal software BANFF.

Designed as a general-purpose tool, GUNDAM is intended for use in a variety of analyses and collaborations.