How to Read Open Office Excel Files in C# Without Excel Installed

How Do You Install IronXL in a .NET Project?

Install-Package IronXL
dotnet add package IronXL

Install-Package IronXL
dotnet add package IronXL

How Do You Load an OpenOffice or Excel File in C#?

IronXL treats ODS, XLS, XLSX, and CSV files identically through the WorkBook.Load method. You pass an absolute or relative file path, and the library detects the format from the file header -- not just the extension. This means a file renamed from .ods to .xlsx is still read correctly.

using IronXL;

// Load an OpenDocument Spreadsheet (.ods) produced by LibreOffice Calc or OpenOffice
WorkBook workbook = WorkBook.Load("quarterly_report.ods");

// Access the first worksheet by index
WorkSheet sheet = workbook.WorkSheets[0];

// Read a cell value
string companyName = sheet["A1"].StringValue;
int recordCount   = sheet["B1"].IntValue;

Console.WriteLine($"Company : {companyName}");
Console.WriteLine($"Records : {recordCount}");

using IronXL;

// Load an OpenDocument Spreadsheet (.ods) produced by LibreOffice Calc or OpenOffice
WorkBook workbook = WorkBook.Load("quarterly_report.ods");

// Access the first worksheet by index
WorkSheet sheet = workbook.WorkSheets[0];

// Read a cell value
string companyName = sheet["A1"].StringValue;
int recordCount   = sheet["B1"].IntValue;

Console.WriteLine($"Company : {companyName}");
Console.WriteLine($"Records : {recordCount}");

Imports IronXL

' Load an OpenDocument Spreadsheet (.ods) produced by LibreOffice Calc or OpenOffice
Dim workbook As WorkBook = WorkBook.Load("quarterly_report.ods")

' Access the first worksheet by index
Dim sheet As WorkSheet = workbook.WorkSheets(0)

' Read a cell value
Dim companyName As String = sheet("A1").StringValue
Dim recordCount As Integer = sheet("B1").IntValue

Console.WriteLine($"Company : {companyName}")
Console.WriteLine($"Records : {recordCount}")

The same call works for XLSX and XLS files -- just change the path. WorkBook.Load returns the same strongly-typed object regardless of source format, so the rest of your code stays identical whether the file originates from Microsoft Excel, LibreOffice, or any other ODF-compliant application.

How Do You Read Every Row and Cell in a Worksheet?

using IronXL;

WorkBook workbook  = WorkBook.Load("customers.xlsx");
WorkSheet worksheet = workbook.WorkSheets[0];

Console.WriteLine($"Total rows    : {worksheet.RowCount}");
Console.WriteLine($"Total columns : {worksheet.ColumnCount}");
Console.WriteLine();

foreach (var row in worksheet.Rows)
{
    foreach (var cell in row)
    {
        if (!cell.IsEmpty)
            Console.Write($"{cell.StringValue,-20}");
    }
    Console.WriteLine();
}

using IronXL;

WorkBook workbook  = WorkBook.Load("customers.xlsx");
WorkSheet worksheet = workbook.WorkSheets[0];

Console.WriteLine($"Total rows    : {worksheet.RowCount}");
Console.WriteLine($"Total columns : {worksheet.ColumnCount}");
Console.WriteLine();

foreach (var row in worksheet.Rows)
{
    foreach (var cell in row)
    {
        if (!cell.IsEmpty)
            Console.Write($"{cell.StringValue,-20}");
    }
    Console.WriteLine();
}

Imports IronXL

Dim workbook As WorkBook = WorkBook.Load("customers.xlsx")
Dim worksheet As WorkSheet = workbook.WorkSheets(0)

Console.WriteLine($"Total rows    : {worksheet.RowCount}")
Console.WriteLine($"Total columns : {worksheet.ColumnCount}")
Console.WriteLine()

For Each row In worksheet.Rows
    For Each cell In row
        If Not cell.IsEmpty Then
            Console.Write($"{cell.StringValue,-20}")
        End If
    Next
    Console.WriteLine()
Next

How Do You Extract Typed Values from Cells?

using IronXL;

WorkBook workbook = WorkBook.Load("inventory.xlsx");
WorkSheet sheet   = workbook.GetWorkSheet("Products");

// Typed accessors handle conversion automatically
string  productName = sheet["A2"].StringValue;
int     quantity    = sheet["B2"].IntValue;
decimal unitPrice   = sheet["C2"].DecimalValue;
bool    inStock     = sheet["D2"].BoolValue;
DateTime? lastAudit = sheet["E2"].DateTimeValue;

Console.WriteLine($"Product  : {productName}");
Console.WriteLine($"Qty      : {quantity}");
Console.WriteLine($"Price    : {unitPrice:C}");
Console.WriteLine($"In Stock : {inStock}");
Console.WriteLine($"Audited  : {lastAudit?.ToString("d") ?? "Never"}");

using IronXL;

WorkBook workbook = WorkBook.Load("inventory.xlsx");
WorkSheet sheet   = workbook.GetWorkSheet("Products");

// Typed accessors handle conversion automatically
string  productName = sheet["A2"].StringValue;
int     quantity    = sheet["B2"].IntValue;
decimal unitPrice   = sheet["C2"].DecimalValue;
bool    inStock     = sheet["D2"].BoolValue;
DateTime? lastAudit = sheet["E2"].DateTimeValue;

Console.WriteLine($"Product  : {productName}");
Console.WriteLine($"Qty      : {quantity}");
Console.WriteLine($"Price    : {unitPrice:C}");
Console.WriteLine($"In Stock : {inStock}");
Console.WriteLine($"Audited  : {lastAudit?.ToString("d") ?? "Never"}");

Imports IronXL

Dim workbook As WorkBook = WorkBook.Load("inventory.xlsx")
Dim sheet As WorkSheet = workbook.GetWorkSheet("Products")

' Typed accessors handle conversion automatically
Dim productName As String = sheet("A2").StringValue
Dim quantity As Integer = sheet("B2").IntValue
Dim unitPrice As Decimal = sheet("C2").DecimalValue
Dim inStock As Boolean = sheet("D2").BoolValue
Dim lastAudit As DateTime? = sheet("E2").DateTimeValue

Console.WriteLine($"Product  : {productName}")
Console.WriteLine($"Qty      : {quantity}")
Console.WriteLine($"Price    : {unitPrice:C}")
Console.WriteLine($"In Stock : {inStock}")
Console.WriteLine($"Audited  : {If(lastAudit?.ToString("d"), "Never")}")

How Do You Work with Multiple Named Worksheets?

using IronXL;

WorkBook workbook = WorkBook.Load("annual_sales.xlsx");

// Option 1: access by name (throws if the sheet does not exist)
WorkSheet januarySheet = workbook.GetWorkSheet("January");

// Option 2: iterate all sheets in the workbook
foreach (WorkSheet ws in workbook.WorkSheets)
{
    Console.WriteLine($"Sheet: {ws.Name}  |  Rows: {ws.RowCount}");

    // Read the header row from each sheet
    string header = ws["A1"].StringValue;
    Console.WriteLine($"  Header: {header}");
}

// Option 3: access by zero-based index
WorkSheet lastSheet = workbook.WorkSheets[workbook.WorkSheets.Count - 1];
Console.WriteLine($"Last sheet: {lastSheet.Name}");

using IronXL;

WorkBook workbook = WorkBook.Load("annual_sales.xlsx");

// Option 1: access by name (throws if the sheet does not exist)
WorkSheet januarySheet = workbook.GetWorkSheet("January");

// Option 2: iterate all sheets in the workbook
foreach (WorkSheet ws in workbook.WorkSheets)
{
    Console.WriteLine($"Sheet: {ws.Name}  |  Rows: {ws.RowCount}");

    // Read the header row from each sheet
    string header = ws["A1"].StringValue;
    Console.WriteLine($"  Header: {header}");
}

// Option 3: access by zero-based index
WorkSheet lastSheet = workbook.WorkSheets[workbook.WorkSheets.Count - 1];
Console.WriteLine($"Last sheet: {lastSheet.Name}");

Imports IronXL

Dim workbook As WorkBook = WorkBook.Load("annual_sales.xlsx")

' Option 1: access by name (throws if the sheet does not exist)
Dim januarySheet As WorkSheet = workbook.GetWorkSheet("January")

' Option 2: iterate all sheets in the workbook
For Each ws As WorkSheet In workbook.WorkSheets
    Console.WriteLine($"Sheet: {ws.Name}  |  Rows: {ws.RowCount}")

    ' Read the header row from each sheet
    Dim header As String = ws("A1").StringValue
    Console.WriteLine($"  Header: {header}")
Next

' Option 3: access by zero-based index
Dim lastSheet As WorkSheet = workbook.WorkSheets(workbook.WorkSheets.Count - 1)
Console.WriteLine($"Last sheet: {lastSheet.Name}")

How Do You Handle Merged Cells and Formatted Regions?

Reports and dashboards frequently use merged cells for headings, grouped labels, and summary rows. IronXL reads the value from the top-left cell of a merged region, exactly as Excel displays it:

using IronXL;

WorkBook workbook = WorkBook.Load("report_with_merges.xlsx");
WorkSheet sheet   = workbook.DefaultWorkSheet;

// The merged region A1:D1 stores its value in cell A1
string reportTitle = sheet["A1"].StringValue;
Console.WriteLine($"Report title : {reportTitle}");

// Read cell formatting metadata
var titleCell = sheet["A1"];
Console.WriteLine($"Bold         : {titleCell.Style.Font.Bold}");
Console.WriteLine($"Font size    : {titleCell.Style.Font.Height}");

// Scan an entire column for non-empty section headers
foreach (var cell in sheet["A1:A100"])
{
    if (!cell.IsEmpty && cell.Style.Font.Bold)
        Console.WriteLine($"Section header at {cell.AddressString}: {cell.StringValue}");
}

using IronXL;

WorkBook workbook = WorkBook.Load("report_with_merges.xlsx");
WorkSheet sheet   = workbook.DefaultWorkSheet;

// The merged region A1:D1 stores its value in cell A1
string reportTitle = sheet["A1"].StringValue;
Console.WriteLine($"Report title : {reportTitle}");

// Read cell formatting metadata
var titleCell = sheet["A1"];
Console.WriteLine($"Bold         : {titleCell.Style.Font.Bold}");
Console.WriteLine($"Font size    : {titleCell.Style.Font.Height}");

// Scan an entire column for non-empty section headers
foreach (var cell in sheet["A1:A100"])
{
    if (!cell.IsEmpty && cell.Style.Font.Bold)
        Console.WriteLine($"Section header at {cell.AddressString}: {cell.StringValue}");
}

Imports IronXL

Dim workbook As WorkBook = WorkBook.Load("report_with_merges.xlsx")
Dim sheet As WorkSheet = workbook.DefaultWorkSheet

' The merged region A1:D1 stores its value in cell A1
Dim reportTitle As String = sheet("A1").StringValue
Console.WriteLine($"Report title : {reportTitle}")

' Read cell formatting metadata
Dim titleCell = sheet("A1")
Console.WriteLine($"Bold         : {titleCell.Style.Font.Bold}")
Console.WriteLine($"Font size    : {titleCell.Style.Font.Height}")

' Scan an entire column for non-empty section headers
For Each cell In sheet("A1:A100")
    If Not cell.IsEmpty AndAlso cell.Style.Font.Bold Then
        Console.WriteLine($"Section header at {cell.AddressString}: {cell.StringValue}")
    End If
Next

The Style property tree mirrors the structure of the OOXML SpreadsheetML specification, so property names feel familiar if you have worked with the Open XML SDK. However, IronXL wraps all of that complexity in a clean API that does not require any XML manipulation on your part.

How Do You Import CSV Files with the Same API?

CSV files produced by database exports, CRM systems, and legacy applications can be read through the same WorkBook.Load call. IronXL infers the delimiter from the file content:

using IronXL;

// Load a comma-separated values file -- same method, same API
WorkBook csvWorkbook  = WorkBook.Load("export.csv");
WorkSheet csvSheet    = csvWorkbook.DefaultWorkSheet;

Console.WriteLine($"CSV rows loaded: {csvSheet.RowCount}");

// Process rows exactly like any other worksheet
foreach (var row in csvSheet.Rows)
{
    string id   = row[0].StringValue;
    string name = row[1].StringValue;
    Console.WriteLine($"{id,-10} {name}");
}

using IronXL;

// Load a comma-separated values file -- same method, same API
WorkBook csvWorkbook  = WorkBook.Load("export.csv");
WorkSheet csvSheet    = csvWorkbook.DefaultWorkSheet;

Console.WriteLine($"CSV rows loaded: {csvSheet.RowCount}");

// Process rows exactly like any other worksheet
foreach (var row in csvSheet.Rows)
{
    string id   = row[0].StringValue;
    string name = row[1].StringValue;
    Console.WriteLine($"{id,-10} {name}");
}

Imports IronXL

' Load a comma-separated values file -- same method, same API
Dim csvWorkbook As WorkBook = WorkBook.Load("export.csv")
Dim csvSheet As WorkSheet = csvWorkbook.DefaultWorkSheet

Console.WriteLine($"CSV rows loaded: {csvSheet.RowCount}")

' Process rows exactly like any other worksheet
For Each row In csvSheet.Rows
    Dim id As String = row(0).StringValue
    Dim name As String = row(1).StringValue
    Console.WriteLine($"{id,-10} {name}")
Next

After loading, you can save the data as XLSX using csvWorkbook.SaveAs("output.xlsx"). This is a common pattern for CSV-to-Excel conversion pipelines -- receive a CSV file, enrich it with calculated columns or formatting, and return a formatted XLSX report to the user.

For tab-separated files or custom delimiters, use WorkBook.LoadCSV("file.tsv", fileFormat: ExcelFileFormat.TSV) to specify the format explicitly.

How Does IronXL Compare to Microsoft.Office.Interop.Excel?

How Do You Deploy Excel Processing to Linux and Docker?

Server deployments are where IronXL's independence from Excel becomes most valuable. The same code you write on Windows runs unchanged on Ubuntu, Alpine Linux, or macOS. For containerized deployments, your Dockerfile requires no special configuration:

# Standard .NET runtime image -- no Office packages needed
FROM mcr.microsoft.com/dotnet/runtime:10.0
WORKDIR /app
COPY --from=build /app/publish .
ENTRYPOINT ["dotnet", "ExcelProcessor.dll"]

# Standard .NET runtime image -- no Office packages needed
FROM mcr.microsoft.com/dotnet/runtime:10.0
WORKDIR /app
COPY --from=build /app/publish .
ENTRYPOINT ["dotnet", "ExcelProcessor.dll"]

For Azure Functions and AWS Lambda, IronXL works within the managed runtime without any additional configuration. The cold-start overhead is minimal because there is no COM initialization step.

Thread safety is built in: multiple threads can open different WorkBook instances concurrently without coordination. If you need to process thousands of files in parallel -- for example, in a background job that ingests user-uploaded spreadsheets -- you can use Parallel.ForEach or Task.WhenAll across a pool of WorkBook instances without risk of corruption.

Memory usage stays predictable because IronXL loads only the requested worksheet into memory, not the entire workbook on initialization. For very large files, this distinction matters: a workbook with ten 50MB sheets does not require 500MB of RAM just to read a single sheet. The IronXL performance documentation covers additional strategies for handling high-volume file processing scenarios.

What Are Your Next Steps?

The quickest way to validate IronXL in your project is to install the NuGet package and run the examples in this guide against a real file from your environment. A free trial license unlocks all features with no code changes required when you are ready for production.

Explore related IronXL capabilities that complement file reading:

• Write and create Excel files in C# -- build reports and data exports programmatically
• Format cells, rows, and columns -- apply colors, fonts, and borders in code
• Work with Excel formulas in C# -- read and write formula cells
• Convert Excel to PDF in .NET -- generate PDF reports from spreadsheet data
• IronXL API documentation -- full reference for all classes and methods
• IronXL licensing and pricing -- options for individual developers and enterprise teams
• IronXL NuGet page -- installation instructions for all project types
• IronXL tutorials -- step-by-step guides for common use cases
• Compare IronXL to EPPlus -- side-by-side feature and licensing comparison
• IronXL product home -- feature overview and getting-started resources

For questions about licensing, cross-platform support, or specific file format requirements, the IronXL support team is available through live chat and email.

Get stated with IronXL now.

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