A-1 Technology, Rich Internet Applications (RIAs) are web applications that have some of the characteristics of desktop applications, typically delivered by way of a proprietary web browser plug-ins or independently via sandboxes or virtual machines. Examples of RIA frameworks include Adobe Flex / AIR, Java / JavaFX and Microsoft Silverlight.

It is now possible to build RIA-like Web applications that run in all modern browsers without the need of special run-times or plug-ins. This means that if one could run a modern Ajax-based Web application outside of a web browser (e.g. using Mozilla Prism or Fluid) it would essentially be an RIA, though there is some contention as to whether this is actually the case.

Accessibility of data to search engines and web accessibility can be impaired. For example, it took over a decade from release for Adobe Flash to be universally searchable.

Advanced communications with supporting servers can improve the user experience, for example, by using optimised network protocols, asynchronous I/O and pre-fetching data (eg Google Maps). Accordingly, reliable broadband connections are often required.

Complexity of advanced solutions can make them more difficult to design, develop, deploy and debug than traditional web applications (but typically less so than application software).

Consistency of user interface and experience can be controlled across operating systems. Performance monitoring and fault diagnosis can be particularly difficult.

Installation and Maintenance of plug-ins, sandboxes or virtual machines is required (but applications are smaller than their predecessors and updates are typically automated). Installation is typically faster than that of application software but slower than that of native web applications and automation may not be possible.

Offline use may be supported by retaining state locally on the client machine, but developments in web standards (prototyped in Google Gears) have also enabled this for native web applications.

Security can improve over that of application software (for example through use of sandboxes and automatic updates) but the extensions themselves are subject to vulnerabilities and access possible is often much greater than that of native web applications.

Performance can improve depending on the application and network characteristics. In particular, applications which can avoid the latency of round-trips to the server by processing locally on the client are often a lot faster. Offloading work to the clients can also improve server performance. Conversely the resource requirements can be prohibitive for small, embedded and mobile devices.

Richness by way of features not supported natively by the web browser such as video capture (eg Adobe Flash).