Learn how to use the ClosedXML NuGet package to export data as a CSV or XLSX file for Excel from an ASP.NET Core application.

Take advantage of the static files middleware in ASP.NET Core to serve HTML, CSS, JavaScript, and images to the client.

Google is your friend. There are a ton of third party libs that will load an excel file into an ado.net dataset. From there you can use the select method to do your search.