It is written as a web-page app. You can, if you want, install the page to your home screen on android and iOS. This makes the page cached and will then work offline.
Munchkin is a trademark of Steve Jackson Games, and its rules and art are copyrighted by Steve Jackson Games. All rights are reserved by Steve Jackson Games. This game aid is the original creation of Matthew Sarsby and is released for free distribution, and not for resale, under the permissions granted in the Steve Jackson Games Online Policy.
GURPS is a registered trademark of Steve Jackson Games, and the art here is copyrighted by Steve Jackson Games. All rights are reserved by SJ Games. This material is used here in accordance with the SJ Games online policy.