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Aspose.Cells FOSS for .NET

Create, modify, and save Excel .xlsx workbooks from .NET — free and open-source, zero Microsoft Office dependency.

Aspose.Cells FOSS for .NET Aspose.Cells FOSS
for .NET

Documentation GitHub

Open-Source .NET Library for Excel Spreadsheets

Aspose.Cells FOSS for .NET is a free, MIT-licensed open-source library for working with Excel spreadsheet files in .NET applications. Install it with a single dotnet add package Aspose.Cells_FOSS command and start creating workbooks, reading cells, applying styles, adding conditional formatting, hyperlinks, data validation, and auto-filters — all without requiring Microsoft Excel or any native Office library.

The library exposes a clean API built around Workbook, Worksheet, Cells, and Cell — the familiar objects every spreadsheet developer knows. Construct a Workbook to load an existing .xlsx file or create a blank one, access worksheets through the Worksheets collection, read and write cell values with PutValue, and apply styles via GetStyle()/SetStyle(). Formulas are stored verbatim as strings and evaluated by the viewer on open, not by the library at runtime.

Because the library is pure managed .NET code with no native dependencies, it runs identically on Windows, macOS, Linux, Docker containers, and serverless environments such as Azure Functions and AWS Lambda. The MIT License permits unrestricted commercial use with no royalties, seat licenses, or per-deployment fees.

Read and Write Excel Files

  • XLSX read/write: Open and save workbooks with full round-trip fidelity using Workbook(fileName) and Save(fileName).
  • Cell values: Write string, int, bool, decimal, and DateTime values with Cell.PutValue(value).
  • Cell access: Read values with Cell.StringValue, Cell.Value, and Cell.IntValue.
  • Formulas: Store formula strings via Cell.Formula — evaluated by Excel on open.
  • Worksheet navigation: Access sheets by index or name via Workbook.Worksheets.

Where Aspose.Cells FOSS for .NET Can Be Used

  • Report generation: Build branded Excel reports in .NET server applications.
  • Data export: Write database query results directly to .xlsx without Office.
  • CI/CD automation: Generate test-result workbooks inside Docker or Linux CI.
  • ETL workflows: Read input sheets, transform data, and write output workbooks.
  • Serverless functions: Run inside Azure Functions or AWS Lambda without dependencies.

Cell Styling and Conditional Formatting

  • Font styling: Apply bold, italic, font size, and color via CellStyle.Font.
  • Fill patterns: Set background colors with CellStyle.ForegroundColor and FillPattern.Solid.
  • Conditional formatting: Add FormatConditionType.CellValue, Expression, ColorScale, DataBar, and IconSet rules via Worksheet.ConditionalFormattings.
  • Style normalization: Use StyleRepository.Normalize(style) for consistent style application.
  • Number formats: Assign custom number format strings per cell.

Formatting Use Cases

  • Dashboard reports: Apply color scales and data bars to highlight KPI ranges.
  • Status sheets: Use icon sets to visually categorize row states.
  • Financial workbooks: Format currency and date columns with built-in number formats.
  • Header styling: Bold and color header rows to distinguish them from data rows.

Data Validation and Auto-Filters

  • Validation rules: Add whole-number, decimal, list, and date validations via ValidationCollection.Add().
  • Operators: Use OperatorType.Between, GreaterThan, LessThan, and others.
  • Validation type: Set ValidationType.WholeNumber, Decimal, List, Date, or Custom.
  • Auto-filters: Apply column filters on a range with AutoFilter and AutoFilter.FilterColumns.
  • Cell areas: Define validation ranges using CellArea.CreateCellArea(start, end).

Validation Use Cases

  • Data entry forms: Restrict input to valid ranges before the workbook is shared.
  • Budget templates: Enforce whole-number budget cells with min/max bounds.
  • Reporting pipelines: Validate output data before delivering to stakeholders.
  • List constraints: Lock cells to a pre-defined dropdown list of allowed values.

Hyperlinks, Named Ranges, and Protection

  • Hyperlinks: Add external URLs, internal cell references, and mailto links via HyperlinkCollection.Add().
  • Named ranges: Define global and sheet-scoped named ranges with DefinedNameCollection.Add().
  • Workbook protection: Lock workbook structure using WorkbookProtection.
  • Worksheet protection: Protect individual sheets with Worksheet.Protect().
  • Load diagnostics: Inspect malformed input using LoadDiagnostics and LoadIssue.

Governance and Collaboration Use Cases

  • Template distribution: Protect sheets to prevent accidental formula overwrite.
  • Shared workbooks: Use named ranges to create stable cross-sheet references.
  • Audit trails: Link cells to external documentation URLs via hyperlinks.
  • Input validation: Combine protection with validation to enforce data governance.

Create a Workbook and Write Cells

Install the NuGet package, then create a Workbook, access the first Worksheet, and write values to cells using PutValue. The example demonstrates writing multiple value types and performing a save-and-reload round trip.

dotnet add package Aspose.Cells_FOSS

using Aspose.Cells_FOSS;

var outputPath = "cell-data-roundtrip.xlsx";
var workbook = new Workbook();
var sheet = workbook.Worksheets[0];

sheet.Cells["A1"].PutValue("Hello");
sheet.Cells["B1"].PutValue(123);
sheet.Cells["C1"].PutValue(true);
sheet.Cells["D1"].PutValue(12.5m);
sheet.Cells["F1"].PutValue(10);
sheet.Cells["G1"].Formula = "=F1*2";
workbook.Save(outputPath);

var loaded = new Workbook(outputPath);
var loadedSheet = loaded.Worksheets[0];
Console.WriteLine(loadedSheet.Cells["A1"].StringValue);
Console.WriteLine(loadedSheet.Cells["G1"].Formula);

Apply Conditional Formatting

Add conditional formatting rules to highlight cell ranges. The example applies a between-value rule with a solid fill, an expression rule, a color scale, a data bar, and an icon set.

using Aspose.Cells_FOSS;

var workbook = new Workbook();
var sheet = workbook.Worksheets[0];
sheet.Name = "Conditional Formatting";

for (var i = 0; i < 10; i++)
    sheet.Cells[i, 0].PutValue(i + 1);

var cfCol = sheet.ConditionalFormattings[sheet.ConditionalFormattings.Add()];
cfCol.AddArea(CellArea.CreateCellArea("A1", "A10"));
var rule = cfCol[cfCol.AddCondition(FormatConditionType.CellValue,
    OperatorType.Between, "3", "7")];
var style = rule.Style;
style.Pattern = FillPattern.Solid;
style.ForegroundColor = Color.FromArgb(255, 255, 199, 206);
style.Font.Bold = true;
rule.Style = style;

workbook.Save("conditional-formatting.xlsx");

Add Hyperlinks and Named Ranges

Create external and internal hyperlinks, then define named ranges scoped to the workbook or a specific sheet.

using Aspose.Cells_FOSS;

var workbook = new Workbook();
var sheet = workbook.Worksheets[0];
sheet.Name = "Links";

sheet.Cells["A1"].PutValue("Docs");
var link = sheet.Hyperlinks[sheet.Hyperlinks.Add("A1", 1, 1, "https://example.com/docs")];
link.TextToDisplay = "Docs";
link.ScreenTip = "External docs";

var name = workbook.DefinedNames[workbook.DefinedNames.Add("GlobalRange", "='Links'!$A$1:$D$5")];
name.Comment = "Primary sample range";

workbook.Save("hyperlinks-and-names.xlsx");

Frequently Asked Questions

What is Aspose.Cells FOSS for .NET?

It is a free, MIT-licensed open-source .NET library for creating, reading, modifying, and saving Excel .xlsx workbooks without requiring Microsoft Office.

Which file formats are supported?

XLSX is the only supported read/write format. XLS, CSV, ODS, PDF, HTML, and image export are not available in this edition.

Does it require Microsoft Office?

No. Aspose.Cells FOSS is pure managed .NET code with no COM, P/Invoke, Office Interop, or native library dependencies.

How do I install it?

Run dotnet add package Aspose.Cells_FOSS. The library requires .NET 6.0 or later. There are no native extensions to compile.

Does the library support formula recalculation?

Formula strings are stored and retrieved verbatim. The library does not perform server-side recalculation — formulas are evaluated by Excel or a compatible application on open.

Can I use it in a commercial product?

Yes. The MIT License permits unrestricted commercial use with no royalties, seat licenses, or per-deployment fees.

  

Support and Learning Resources

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