How can I sign a PDF with an external signing service?
In practical usage, more often than not, you will be relying on external devices like USB tokens, smart cards, and other hardware devices for storing your key pairs. This is why UniPDF supports signing your PDF documents with the help of external devices.
UniPDF is written in Go, which is flexible, fast, and will allow you to safely link up and read from your external devices. Since Go is cloud-friendly, you can build an efficient enterprise solution that will allow your users to connect their hardware devices and easily sign PDF documents without compromising their keys.
You can check out the example here to learn how such a service can be built by using UniPDF.