Cloud APIs & SDKs for adding watermark for Microsoft Excel & OpenOffice Calc. Adding watermark for local spreadsheets by the Cells Cloud API. SDK support kinds of development languages. They include Android, C#, Go, Java, NodeJS, Perl, PHP, Python, Ruby, and swift....Cells .NET Background ADD-WATERMARK Background...OpenOffice Calc spreadsheet Use Cells Watermark REST API to add watermark...