Key features of the framework include:

Core

• Pluggable framework architecture that allows request lifecycles to be customized for each action.
• Flexible Validation framework that allows validation rules to be decoupled from action code.
• Hierarchical approach to internationalization that simplifies localizing applications.
• Automatic Type Conversion that transparently maps values from HTTP to native Java data objects, solving one of the most tedious efforts when creating web applications.
• Integrated Dependency Injection engine that manages component lifecycle and dependencies. (By default, the framework utilizes Spring for dependency injection.)
• Modular Configuration Files that use packages and namespaces to simplify managing large projects with hundreds of actions.
• Java 5 annotations that reduce configuration overhead. (Java 1.4 is the minimum platform.)

View

• Reusable user interface tags that allow for easy component-oriented development using Themes and Templates. Bundled tags ranges from simple text fields to advanced tags like date pickers and tree views.
• JSTL-compatible expression language (OGNL) that exposes properties on multiple objects as if they were a single JavaBean.
• Pluggable Result Types that support multiple view technologies, including JSP, FreeMarker, Velocity, PDF, and JasperReports.
• Optional ajax theme that simplifes creating interactive web applications.
• Optional Interceptor plugins that can execute long-running queries in the background, prevent multiple form submissions, or handle custom security schemes.

Other

• Easy integration with other popular products, including Hibernate, Spring, SiteMesh, and JSTL.
• Distributed under the business-friendly Apache License 2.0.