Input validation in web applications represents an important part of their functionality. With proper validation we ensure that provided input data is in accordance with technical constraints, defined by the developer and with business-related constraints. In web development frameworks, validation logic is coupled with program code. If one validation rule is changed, application needs to be recompiled and redeployed. In this thesis we developed a system for input validation based on business rules management system. Validation rules are stored in central repository, separated from implementation of web applications. Thus, we have achieved a simple and transparent way of declaring validation logic in the form of declarative business rules as well as simplifed applications maintenance in case of changes in validation logic.