Rapid prototyping is the process of making a realistic model of a future program or programmable product's user interface in order to gain early insight into the usability, needs and functions of the product. Rapidly prototyped user interfaces are easy to modify and allow the end user to provide input into the design. Although rapid prototyping offers the advantage of user input in design and the ability to detect and correct flaws during development, there are several challenges that arise as well.

Reusable Code Issues

Some prototyping tools allow the programmer to produce reusable code, but these produce user interfaces that are difficult to revise later. The more common approach, using tools that allow the quick development of user interfaces that are easier to modify, does not produce usable code. The code generated by these tools is highly specialized and integrated in complex ways that prevent its being effectively reproduced in part or transferred to another application. In most cases, the benefit of using faster prototyping tools is greater customer satisfaction and a product that is more likely to serve the customer's preferences, priorities and requirements. Given these advantages, the disadvantage of lacking reusable code is often considered an acceptable sacrifice in rapid prototyping.

Slower Development Process

Direct involvement of the client in the development process has the potential to introduce new needs and features that will require further coding. While this can enhance both the client's experience in development and the usability of the final product, every new specification introduced will add to the overall time it takes to complete development. In cases where several new needs are discovered throughout the process of rapid prototyping, the otherwise minor delays caused by each of these changes can add up to a significant delay.

Stopping Point

Developers who can add or modify features at any time run the risk of developing an interface to which they will always want to add. The potential to integrate countless additional improvements can stretch the time it takes to develop a product just as much as the client's involvement can, as noted above. Without a strict stopping point imposed by schedules, deadlines or budget limits, the project could stay in development indefinitely and a finished, marketable product may never see the light of day.