Looking for free/open source .docx to .pdf converter

Hello, I'm looking for a package I can use in my .net code to convert some .docx to .pdf they need to look 1:1 the same, because they will be sent out to customers, I found some and they don't seem to work or don't preserve the right format of our .docx files, the only option I found and easy to use was a paid option (spire.doc).

So does anyone know an easy to use option for me? thanks