https://github.com/dotnet/Open-XML-SDK
First party from Microsoft; feels like it would be the way to go.
That is the source of DocumentFormat.OpenXml, you're talking about the same package, https://github.com/dotnet/Open-XML-SDK#packages
Microsoft are incapable of:
1. naming things well 2. keeping those names stable
That is the source of DocumentFormat.OpenXml, you're talking about the same package, https://github.com/dotnet/Open-XML-SDK#packages
Microsoft are incapable of: