I need to implement a system in Spring Boot and logical document to manage document which provide the feature to add either digital signature or Esignature to word document/PDF file while it is being uploaded on the system.

I have seen there are many tools that I can use to integrate as REST API to generate either e-signature or digital signature as follows:

1. Docusign – Robust , widely used and expensive compared to PandaDoc
   and DocuSeal
2. Docuseal – Robust support signature but I does not look like it
   support digital signature.
3. PandaDoc – Robust and ideal for businesses needing comprehensive
   document management but support only esignature not digital
   signature.

Based on the above it looks like only docuSign support digital signature and esignature.

I am new to the above tools and I might have missed something important or any other tool. Any advice on which one is easier to integrate as API to generate either digital signature or esignature?

Thanks in advance.