The use of Ajax, or Asynchronous JavaScript + XML, can result in Web applications that demonstrate the flexibility, responsiveness, and usability traditionally found only in desktop software. To illustrate this, a repository metasearch user interface, OJAX, has been developed. OJAX is simple, unintimidating but powerful. It attempts to minimize upfront user investment and provide immediate dynamic feedback, thus encouraging experimentation and enabling enactive learning. This article introduces the Ajax approach to the development of interactive Web applications and discusses its implications. It then describes the OJAX user interface and illustrates how it can transform the user experience