Follow this article to sign PDF using C# REST API. You will learn to electronically sign PDF using C# .NET-based API with a .NET-based Cloud SDK. It will assist in uploading the target PDF file and signature file to the Cloud storage and then use the signature file to sign the PDF.
Prerequisite
- Create an account API credentials to add a signature to PDF
- Download Aspose.PDF Cloud SDK for Dotnet for electronically signing PDF
- Setup C# project with the above SDK
Steps to Sign PDF Online using C# REST Interface
- Create a PdfApi instance using your Client ID and Client Secret credentials
- Specify the PDF file name, signature file name, and storage folder path
- Set the signature’s position and size on the PDF page using Rectangle
- Initialize a Signature instance with path, type, password, and visual properties
- Populate metadata such as authority, location, contact, and signing date
- Upload both the PDF and the certificate file to the configured folder
- Call PostSignDocument to apply the digital signature to the uploaded PDF
- Retrieve the signed document stream and write it locally as Sample_out.pdf
These steps summarize how to digitally sign PDF using C# REST API. This code connects to Aspose.PDF Cloud, uploads a PDF and a certificate, then digitally signs the document using the provided credentials and signature details. After signing, it downloads the updated PDF and saves it locally as a new file.
Code to Add Signature to PDF using C# RESTful Service
This code demonstrates the process to sign PDF documents using C# Low Code API. Note that for signing a PDF file, it should have the form field of Signature type and its name should be known. You will get an error if the PDF does not contain a Signature type field or if the wrong field name is used.
This article has taught us the process of signing a PDF file. To compress a PDF file, refer to the article on Compress PDF with C# REST API.
