The feature we were trying to add was one that allowed our users to include a visual signature to PDF files. One of the key requirements for this feature was that we cannot use any third party control/product that required us to post/forward (implicitly or explicitly) the PDF file to their hosted site. We needed a control/product that we can deploy fully on our servers with no outbound posts to their product’s site. Using Aspose.Pdf for .NET, here is how we solved our use case:

1. We converted the PDF to an image file using Aspose.
2. We then displayed this PDF image to the user for identifying the signature sections in the PDF. (We created a transparent DIV that the user could drag on top of this PDF image for this purpose)
3. Each signature section was uniquely ID’d.
4. We used one of the common jQuery plug-ins for capturing the user’s name/signature in different font styles. This plug-in also allowed the user to draw their signature.
5. When the appropriate reviewer was ready to sign the document, we use the Aspose.NET for PDF code to place the signature image on the PDF file.

Though we had to jump through a few hoops, Aspose.Pdf for .NET was able to help us meet our needs in a cost effective manner. As others have noted in their reviews, their price is a bit high, but compared to others in the market place, they are still on the affordable side.