https://demos.telerik.com/aspnet-ajax/grid/examples/functionality/grouping/clientdatasource-grouping/defaultcs.aspx?skin=Glow
Telerik Web UI Grid Grouping Client-Side with RadClientDataSource Demo | Telerik UI for ASP.NET AJAX
Telerik WebForms Grid Grouping Client-Side with RadClientDataSource. Learn more about Grid for ASP.NET AJAX and get a free trial today.