nissl-lab / npoi

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

dotnet / Open-XML-SDK

Open XML SDK by Microsoft

mini-software / MiniExcel

Lightweight, fast and native cross-platform processing tool for importing and exporting spreadsheet documents.

EvotecIT / OfficeIMO

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