Top 20 NuGet openXML Packages

Facilitates streaming simple string values to XLSX (Excel 2007+ files)
Extends the Open XML framework
Library for generating DOCX documents based on templates in DOCX format with all features of MS Word available
Customizable open source library for validating generic file formats (size, extension, file signature, checksum etc.) with available extensions which can detect corrupted files of some popular file formats.