Thanks for your interest in our API’s.
We have an API named Aspose.Pdf for .NET which offers the feature to create as well as manipulate existing PDF files. It also offers the feature to convert XML and XSL-FO files to PDF format but I am afraid it does not offer the feature to convert PDF file to XSL-FO.
However you can transform PDF file to XML format and then you can perform XML to XSL-FO conversion.
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