Generating Word, Excel, and PDF Documents Dynamically in ASP.NET Core

using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;

public class WordService
{
    public byte[] GenerateDocument(string title, string content)
    {
        using var ms = new MemoryStream();
        using (var doc = WordprocessingDocument.Create(ms,
            DocumentFormat.OpenXml.WordprocessingDocumentType.Document))
        {
            var main = doc.AddMainDocumentPart();
            main.Document = new Document();
            var body = main.Document.AppendChild(new Body());

            body.AppendChild(new Paragraph(
                new Run(new Text(title))));

            body.AppendChild(new Paragraph(
                new Run(new Text(content))));
        }
        return ms.ToArray();
    }
}

Part 2: Generate Excel (.xlsx) Using OpenXML

ExcelService.cs

using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Spreadsheet;

public class ExcelService
{
    public byte[] GenerateExcel(List<string> rows)
    {
        using var ms = new MemoryStream();
        using (var doc = SpreadsheetDocument.Create(ms, SpreadsheetDocumentType.Workbook))
        {
            var wbPart = doc.AddWorkbookPart();
            wbPart.Workbook = new Workbook();

            var wsPart = wbPart.AddNewPart<WorksheetPart>();
            var sheetData = new SheetData();
            wsPart.Worksheet = new Worksheet(sheetData);

            foreach (var rowVal in rows)
            {
                var row = new Row();
                row.Append(new Cell() { DataType = CellValues.String, CellValue = new CellValue(rowVal) });
                sheetData.Append(row);
            }

            var sheets = doc.WorkbookPart.Workbook.AppendChild(new Sheets());
            sheets.Append(new Sheet() { Id = doc.WorkbookPart.GetIdOfPart(wsPart), SheetId = 1, Name = "Sheet1" });
        }
        return ms.ToArray();
    }
}

Part 3: Generate PDF Using QuestPDF

Install package

dotnet add package QuestPDF

PdfService.cs

using QuestPDF.Fluent;
using QuestPDF.Infrastructure;

public class PdfService
{
    public byte[] GeneratePdf(string header, string text)
    {
        var doc = Document.Create(container =>
        {
            container.Page(page =>
            {
                page.Margin(30);
                page.Header().Text(header).FontSize(20).Bold();
                page.Content().Text(text).FontSize(12);
            });
        });

        return doc.GeneratePdf();
    }
}

API Controller

ExportController.cs

[ApiController]
[Route("api/[controller]")]
public class ExportController : ControllerBase
{
    private readonly WordService _word;
    private readonly ExcelService _excel;
    private readonly PdfService _pdf;

    public ExportController(WordService word, ExcelService excel, PdfService pdf)
    {
        _word = word;
        _excel = excel;
        _pdf = pdf;
    }

    [HttpGet("word")]
    public IActionResult ExportWord()
    {
        var file = _word.GenerateDocument("Report", "This is sample Word content.");
        return File(file, "application/vnd.openxmlformats-officedocument.wordprocessingml.document", "report.docx");
    }

    [HttpGet("excel")]
    public IActionResult ExportExcel()
    {
        var file = _excel.GenerateExcel(new List<string> { "Row 1", "Row 2" });
        return File(file, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "report.xlsx");
    }

    [HttpGet("pdf")]
    public IActionResult ExportPdf()
    {
        var file = _pdf.GeneratePdf("PDF Title", "This is PDF content.");
        return File(file, "application/pdf", "report.pdf");
    }
}

Angular Code to Download File

downloadFile(type: string) {
  this.http.get(`api/export/${type}`, { responseType: 'blob' })
    .subscribe(blob => {
      const url = window.URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url;
      a.download = `report.${type}`;
      a.click();
    });
}

Database Scripts (Export Log)

CREATE TABLE ExportLog (
    LogId INT IDENTITY(1,1) PRIMARY KEY,
    FileName VARCHAR(200),
    FileType VARCHAR(50),
    CreatedBy VARCHAR(150),
    CreatedDate DATETIME DEFAULT GETDATE()
);

Best Practices

• Use background jobs for large exports

• Add file caching if frequently downloaded

• Use GUID filenames

• Avoid generating files on disk; use memory stream

Conclusion

You have now seen a full, practical solution for generating Word, Excel, and PDF documents using ASP.NET Core.
With this approach, you can build:

• Complex dynamic reports

• Invoices

• Certificates

• Dashboard exports

• Automated scheduled reports