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ClosedXML is a .NET library for reading, manipulating and writing Excel 2007+ (.xlsx, .xlsm) files. It aims to provide an intuitive and user-friendly interface to dealing with the underlying OpenXML API.

For more information see the documentation or the wiki.

The public API is still not stable and it is a very good idea to read release notes and migration guide before each update.

• Release notes for 0.100
• Migration guide for 0.100
• Release notes for 0.97

Performance matters mostly for large files. For small files, few ms here or there doesn't matter. The presented data are from generally develop branch (currently 0.103-beta).

Load tests used files created during save test.

• If you get an exception Unable to find font font name or fallback font fallback font name. Install missing fonts or specify a different fallback font through ‘LoadOptions.DefaultGraphicEngine = new DefaultGraphicEngine(“Fallback font name”)’, see help page about missing fonts.
• ClosedXML is not thread-safe. There is no guarantee that parallel operations will work. The underlying OpenXML library is also not thread-safe.
• If you get an exception The type initializer for 'Gdip' threw an exception. on Linux, you have to upgrade to 0.97+.

If you want to include ClosedXML in your project, you can install it directly from NuGet

To install ClosedXML, run the following command in the Package Manager Console

PM> Install-Package ClosedXML

ClosedXML allows you to create Excel files without the Excel application. The typical example is creating Excel reports on a web server.

Example:

using (var workbook = new XLWorkbook())
{
    var worksheet = workbook.Worksheets.Add("Sample Sheet");
    worksheet.Cell("A1").Value = "Hello World!";
    worksheet.Cell("A2").FormulaA1 = "=MID(A1, 7, 5)";
    workbook.SaveAs("HelloWorld.xlsx");
}

Be sure to check out our ClosedXML extension projects

• https://github.com/ClosedXML/ClosedXML.Report
• https://github.com/ClosedXML/ClosedXML.Extensions.AspNet
• https://github.com/ClosedXML/ClosedXML.Extensions.Mvc
• https://github.com/ClosedXML/ClosedXML.Extensions.WebApi

The OpenXML specification is a large and complicated beast. In order for ClosedXML, the wrapper around OpenXML, to support all the features, we rely on community contributions. Before opening an issue to request a new feature, we'd like to urge you to try to implement it yourself and log a pull request.

Please read the full developer guidelines.

• Project originally created by Manuel de Leon
• Current maintainer: Jan Havlíček
• Former maintainer and lead developer: Francois Botha
• Master of Computing Patterns: Aleksei Pankratev
• Logo design by @Tobaloidee