Esri’s Web AppBuilder for ArcGIS is a powerful and easy to use out of the box solution for building Web Applications that utilize data hosted as services in ArcGIS Online or Portal for ArcGIS. If out of the box Web AppBuilder components do not fulfill all required functionality, custom widgets can be added to a Web AppBuilder solution. These widgets can be developed using Web AppBuilder Developer Edition and/or users can download already developed widgets from Esri’s GeoNet Community site. However, there are specific requirements that must be met in order to customize and deploy a custom Web AppBuilder solution. This presentation will provide guidelines to help determine if customizing Web AppBuilder is the right choice for you. GeoDecisions has developed several custom widgets in Web AppBuilder. These widgets will be showcased during the presentation as well as lessons learned when developing the widgets.