Features

Features

Aspose.Cells FOSS for .NET is a pure managed .NET library for creating, reading, and modifying Excel XLSX spreadsheets. The entry point is the Workbook class, which provides access to worksheets, defined names, and save/load operations. This page summarises every major feature area with brief code examples.

Workbook Create, Load, and Save

Create a new workbook with new Workbook(). Load an existing XLSX file by passing a file path to the constructor. Use LoadOptions to enable fault-tolerant loading. Call Workbook.Save(path) to persist changes.

using Aspose.Cells_FOSS;

// New workbook
var wb = new Workbook();
wb.Worksheets[0].Cells["A1"].PutValue("Hello");
wb.Save("output.xlsx");

// Load with repair options
var opts = new LoadOptions { TryRepairPackage = true, TryRepairXml = true };
try
{
    var loaded = new Workbook("input.xlsx", opts);
    Console.WriteLine(loaded.Worksheets[0].Cells["A1"].StringValue);
}
catch (WorkbookLoadException ex)
{
    Console.WriteLine("Load failed: " + ex.Message);
}

Cell Data and Formulas

Use Cell.PutValue() to write strings, integers, decimals, booleans, and DateTime values. Set Cell.Formula to assign an Excel-compatible formula string. Read back display text via Cell.StringValue and the raw value via Cell.Value.

using Aspose.Cells_FOSS;

var wb = new Workbook();
var ws = wb.Worksheets[0];

ws.Cells["A1"].PutValue("Qty");
ws.Cells["B1"].PutValue("Price");
ws.Cells["C1"].PutValue("Total");
ws.Cells["A2"].PutValue(10);
ws.Cells["B2"].PutValue(4.99m);
ws.Cells["C2"].Formula = "=A2*B2";

wb.Save("data.xlsx");

var loaded = new Workbook("data.xlsx");
Console.WriteLine(loaded.Worksheets[0].Cells["C2"].StringValue); // 49.9

Cell Styling

Retrieve and modify the Style object for any cell with Cell.GetStyle() and Cell.SetStyle(). The Style class provides Font (bold, italic, size, name), ForegroundColor, Pattern (of type FillPattern), HorizontalAlignment (using HorizontalAlignmentType), and border control through Borders.

using Aspose.Cells_FOSS;

var wb = new Workbook();
var cell = wb.Worksheets[0].Cells["A1"];
cell.PutValue("Styled Header");

var style = cell.GetStyle();
style.Font.Bold = true;
style.Font.Size = 14;
style.Pattern = FillPattern.Solid;
style.ForegroundColor = System.Drawing.Color.FromArgb(255, 198, 239, 206);
style.HorizontalAlignment = HorizontalAlignmentType.Center;
cell.SetStyle(style);

wb.Save("styled.xlsx");

Conditional Formatting

Worksheet.ConditionalFormattings returns a ConditionalFormattingCollection. Call Add() to create a rule set, then AddCondition() to add rules using FormatConditionType and OperatorType. Supported condition types include CellValue, Expression, ColorScale, DataBar, and IconSet.

using Aspose.Cells_FOSS;

var wb = new Workbook();
var ws = wb.Worksheets[0];
for (var i = 0; i < 10; i++)
    ws.Cells[i, 0].PutValue(i + 1);

var ruleSet = ws.ConditionalFormattings[ws.ConditionalFormattings.Add()];
ruleSet.AddArea(CellArea.CreateCellArea("A1", "A10"));
var rule = ruleSet[ruleSet.AddCondition(FormatConditionType.CellValue, OperatorType.Between, "3", "7")];
var ruleStyle = rule.Style;
ruleStyle.Pattern = FillPattern.Solid;
ruleStyle.ForegroundColor = System.Drawing.Color.FromArgb(255, 255, 199, 206);
rule.Style = ruleStyle;

wb.Save("cf.xlsx");

Data Validation

Worksheet.Validations returns a ValidationCollection. Call Add(CellArea) to create a Validation for a cell range. Set the Type property using ValidationType (List, Decimal, or Custom). Configure Formula1, Formula2, Operator, InputTitle, InputMessage, ErrorTitle, and ErrorMessage.

using Aspose.Cells_FOSS;

var wb = new Workbook();
var ws = wb.Worksheets[0];

var listVal = ws.Validations[ws.Validations.Add(CellArea.CreateCellArea("A1", "A10"))];
listVal.Type = ValidationType.List;
listVal.Formula1 = "\"Open,Closed,Pending\"";
listVal.InCellDropDown = true;

var numVal = ws.Validations[ws.Validations.Add(CellArea.CreateCellArea("B1", "B10"))];
numVal.Type = ValidationType.Decimal;
numVal.Operator = OperatorType.Between;
numVal.Formula1 = "0";
numVal.Formula2 = "100";
numVal.ShowError = true;

wb.Save("validation.xlsx");

Auto-Filter

Worksheet.AutoFilter exposes the AutoFilter object. Set AutoFilter.Range to define the header row range. Access AutoFilter.FilterColumns (a FilterColumnCollection) and call Add(columnIndex) to activate filtering on a specific column.

using Aspose.Cells_FOSS;

var wb = new Workbook();
var ws = wb.Worksheets[0];

ws.Cells["A1"].PutValue("Name");
ws.Cells["B1"].PutValue("Region");
ws.Cells["C1"].PutValue("Sales");
ws.Cells["A2"].PutValue("Alice"); ws.Cells["B2"].PutValue("North"); ws.Cells["C2"].PutValue(1200);

ws.AutoFilter.Range = "A1:C1";
ws.AutoFilter.FilterColumns.Add(1);

wb.Save("filter.xlsx");

Hyperlinks and Defined Names

Worksheet.Hyperlinks is a HyperlinkCollection. Call Add() to insert external URLs, internal cell references, or mailto links. Set Hyperlink.TextToDisplay and Hyperlink.ScreenTip for user-facing text. Workbook.DefinedNames is a DefinedNameCollection; call Add(name, refersTo) to create named ranges.

using Aspose.Cells_FOSS;

var wb = new Workbook();
var ws = wb.Worksheets[0];

ws.Cells["A1"].PutValue("Docs");
var link = ws.Hyperlinks[ws.Hyperlinks.Add("A1", 1, 1, "https://docs.aspose.org/cells/net/")];
link.TextToDisplay = "Documentation";

wb.DefinedNames[wb.DefinedNames.Add("DataRange", "Sheet1!$A$1:$D$10")].Comment = "Main data range";

wb.Save("links.xlsx");

Page Setup

Worksheet.PageSetup controls print margins, orientation, paper size, print area, title rows/columns, headers, footers, and page breaks. Use PageOrientationType and PaperSizeType enums.

using Aspose.Cells_FOSS;

var wb = new Workbook();
var ps = wb.Worksheets[0].PageSetup;
ps.Orientation = PageOrientationType.Landscape;
ps.PaperSize = PaperSizeType.PaperA4;
ps.PrintArea = "$A$1:$H$50";
ps.CenterHeader = "My Report";
ps.CenterHorizontally = true;
ps.AddHorizontalPageBreak(25);

wb.Save("paged.xlsx");

Worksheet Management

Add, rename, hide, and reorder worksheets through WorksheetCollection. WorksheetCollection.Add(name) returns the index of the new sheet. Set Worksheet.VisibilityType using VisibilityType. Merge cells with Cells.Merge() and control row/column sizing via Cells.Rows and Cells.Columns.

using Aspose.Cells_FOSS;

var wb = new Workbook();
wb.Worksheets[0].Name = "Summary";
var dataIdx = wb.Worksheets.Add("Data");
wb.Worksheets[dataIdx].VisibilityType = VisibilityType.Hidden;
wb.Worksheets.ActiveSheetName = "Summary";

var ws = wb.Worksheets["Summary"];
ws.Cells["A1"].PutValue("Title");
ws.Cells.Merge(0, 0, 1, 4);
ws.Cells.Rows[0].Height = 30d;
ws.Cells.Columns[0].Width = 20d;

wb.Save("worksheets.xlsx");

Tips and Best Practices

• Always catch WorkbookLoadException when loading files from user-supplied paths.
• Use Cell.PutValue() with the exact .NET type you intend to store — pass decimal for currency, DateTime for dates.
• Read Cell.StringValue for display text; use Cell.Value when you need the raw .NET object.
• Create conditional formatting rule sets on the widest range you need — per-row rules are expensive in large sheets.
• Call wb.Save() once at the end rather than after every cell write.

Common Issues

FAQ

Does Aspose.Cells FOSS for .NET require Microsoft Office?

No. The library is pure managed code with no dependency on Office, Excel, or COM interop.

Which file formats are supported?

XLSX (read and write). CSV, ODS, PDF, and binary XLS are not supported in this release.

Can I use this library in a commercial application?

Yes. Aspose.Cells FOSS is published under the MIT License, which permits unrestricted commercial use with no royalties.

What is the minimum .NET version?

.NET 6.0 or later.

How do I apply a background colour to a cell?

Set style.Pattern = FillPattern.Solid and style.ForegroundColor = System.Drawing.Color.FromArgb(...), then call cell.SetStyle(style).

API Reference Summary