The article presents information regarding the rich Internet applications (RIA), technologies support for the development of RIA applications and methods dedicated to RIA designing. RIA can be defined as „an intersection between Web applications and desktop traditional applications, a part of processing being transferred on a Web client, and the other part being carried out on the application server”. RIA technologies provide, in addition, to traditional Web applications characterised by implementation, administration capacity and availability, a range of new facilities as usability, responsiveness, reusability of client / server applications. RIA applications provide the flexibility in usage specific to a desktop intelligent application and add the wide capabilities of the traditional Web applications to a new type of Web experience which is challenging, interactive, „lightweight” and flexible through the used support technologies.