JudoHD is a free app that explains all the techniques and actions required to achieve a new belt in Judo. The app covers everything from white to yellow to brown belts, with detailed descriptions and illustrations. JudoHD is not only useful for learning new belts, but also provides encyclopedias for general Judo concepts, techniques, and fighters. Additionally, the app includes a list of games that can be used to liven up training sessions.

JudoHD is currently in beta, so there may be some bugs and not all functions are available. However, the developer is constantly working on the app, with plans to add more features such as the ability to download videos of the techniques. The app is based on the examination content that the DJB issued on November 16th, 2014, and will be updated promptly with any changes made by the DJB.

Overall, JudoHD is a great free resource for anyone looking to learn Judo techniques and concepts. It's easy to use, informative, and constantly being updated with new features.