openxml

a .NET library that can read/write Office formats without Microsoft Office installed. No COM+, no interop.

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.

Lightweight, fast and simple cross-platform processing tool for importing and exporting spreadsheet documents. Built in .NET, with Rust bindings.

MIT-licensed, COM-free .NET libraries for creating, reading, editing, converting, rendering, and extracting Office, PDF, email, OneNote, and text formats.