Embodiments of the present invention provide a method and system for scenario-based conceptualization and visualization of web-based user interface for effort estimation. The method includes providing user-selectable scenarios on said web-based user interface. A plurality of web components is provided on pre-populated screen to display existing number of screens, further user can modify the screen by adding new functionality based on business requirement. After modification, a workflow is stored in a repository for proposing it as pre-populated screen to new users. An effort is estimated by an effort estimation processor based on said modified user-selectable scenarios and compliance standard, and a report is generated for each stage of the development cycle.