ClosedXML - The easy way to OpenXML

https://github.com/ClosedXML/ClosedXML
closedxml.zip (108,9 MB)
ClosedXML makes it easier for developers to create Excel 2007+ files.

ExcelPackage: Office Open XML Format file creation

ExcelPackage.zip (4,4 MB)
ExcelPackage provides server-side generation of Excel spreadsheets

NPOI

https://github.com/tonyqus/npoi
npoi.zip (120,3 MB)
.net port of Apache POI

PHPExcel (OLD DEAD REPOSITORY) - visit PHPOffice/PHPExcel on github instead

https://github.com/PHPOffice/PHPExcel
PHPExcel.zip (126,9 MB)
PHPExcel (OLD DEAD REPOSITORY) - visit PHPOffice/PHPExcel on github instead