EPPLUS - c#

Example.cs

[Authorize]
public ActionResult Export() {
    try
    {
        var fileDownloadName = "FileName-" + DateTime.Now.ToShortDateString() + ".xlsx";
        const string contentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";

        var clients = this._clientsRepository.Get();
        
        var package = new ExcelPackage();
        var ws = UtilsCsv.CreateSheet(package, "Client Details", 1);

        //Header
        ws.Cells[1, 1].Value = "Id";
        ws.Cells[1, 2].Value = "Website";
        ws.Cells[1, 3].Value = "Name";
        ws.Cells[1, 4].Value = "Email";
        ws.Cells[1, 5].Value = "Company";
        ws.Cells[1, 6].Value = "File Name";
        ws.Cells[1, 7].Value = "Newsletter";

        ws.Cells[1, 1].Style.Font.Bold = true;
        ws.Cells[1, 2].Style.Font.Bold = true;
        ws.Cells[1, 3].Style.Font.Bold = true;
        ws.Cells[1, 4].Style.Font.Bold = true;
        ws.Cells[1, 5].Style.Font.Bold = true;
        ws.Cells[1, 6].Style.Font.Bold = true;
        ws.Cells[1, 7].Style.Font.Bold = true; 

        //Body
        var n = 2;
        var site = this._siteRepository.Get();

        foreach (var client in clients) {
            ws.Cells[n, 1].Value = client.id;
            ws.Cells[n, 2].Value = site.Where(s => s.id == client.siteId).Select(s => s.name).FirstOrDefault();
            ws.Cells[n, 3].Value = client.name;
            ws.Cells[n, 4].Value = client.email;
            ws.Cells[n, 5].Value = client.company;
            ws.Cells[n, 6].Value = client.fileName;
            ws.Cells[n, 7].Value = client.allowNews;
        }

        var fileStream = new MemoryStream();
        package.SaveAs(fileStream);
        fileStream.Position = 0;
        var fsr = new FileStreamResult(fileStream, contentType) { FileDownloadName = fileDownloadName };

        return fsr;
    }
    catch (Exception) {
        return RedirectToAction("Index", "Clients", new { errors = true }); 
    } 
}

UtilsCsv.cs

using OfficeOpenXml;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;

/// <summary>
/// Create Excel Worksheet: here is the function which creates a worksheet
/// </summary>
/// <param name="p"></param>
/// <param name="sheetName"></param>
/// <param name="sheetId"></param>
/// <returns></returns>
public static ExcelWorksheet CreateSheet(ExcelPackage p, string sheetName, int sheetId)
{
    p.Workbook.Worksheets.Add(sheetName);
    ExcelWorksheet ws = p.Workbook.Worksheets[sheetId];
    ws.Name = sheetName; //Setting Sheet's name
    ws.Cells.Style.Font.Size = 11; //Default font size for whole sheet
    ws.Cells.Style.Font.Name = "Calibri"; //Default Font name for whole sheet
    return ws;
}