Every filter, sort, page and group operations are performed on the datasource not on the data in RadGrid. So, if you want to filter the data and the grid is bind using server-side binding, then you will need to go the server to filter the data and then the returned data by the datasource will be shown in RadGrid on the client.
The only way to filter data on the client is to use client-side binding
All the best,
the Telerik team
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