Web-based applications and desktops

Ajax has prompted the development of websites that mimic desktop applications, such as word processing, the spreadsheet, and slide-show presentation. WYSIWYG wiki sites replicate many features of PC authoring applications. Still other sites perform collaboration and project management functions. In 2006 Google, Inc. acquired one of the best-known sites of this broad class, Writely.

Several browser-based "operating systems" have emerged, including EyeOS and YouOS. Although coined as such, many of these services function less like a traditional operating system and more as an application platform. They mimic the user experience of desktop operating-systems, offering features and applications similar to a PC environment, as well as the added ability of being able to run within any modern browser.

Numerous web-based application services appeared during the dot-com bubble of 1997–2001 and then vanished, having failed to gain a critical mass of customers. In 2005, WebEx acquired one of the better-known of these, Intranets.com, for USD45 million.

Another example of a web-based service that didn't survive the dot-com bubble burst was Pets.com. Pets.com business model was flawed in that the products they were selling and delivering to customers' doorsteps had very thin margins and were expensive to ship.