The home of Judo. This is the Dojo and organisation that Jigoro Kano set up more than 100 years ago to administer and to be the 'home' of Judo.
The website contains details about training at the Kodakan (if you should happen to be in Japan) and the rules, bylaws and techniques of Judo. It is interesting, but not as detailed and complete as Judo Info above.
The world governing body for Judo. Whereas the Kodokan is a 'all Japan' organisation, the IJF consists of a committee selected from all over the world. Often at odds with the Kodokan, the IJF is responsible for the organisation of Judo at international level in the Olympics and World Championships amongst others.