A system and method for automatically performing validation and/or formatting procedures for a graphical user interface (GUI) described in a markup language file. The GUI markup language description may comprise descriptions of various types of GUI elements for which text is to be validated/formatted, such as form fields, tables, hypertext links, etc. The markup language file may include various custom markup language attributes in order to automatically validate/format text for a GUI element. Validation/formatting procedures for GUI elements may thus be based on custom markup language attributes and are managed by a manager that is automatically instantiated when the application parses the markup language file. This manager interfaces to receive programmatic events that trigger various types of formatting/validating operations to be performed on the GUI elements.