Electronic Signature Document Management System

We are looking for someone to develop Document management System that is capable of getting employee w4s, I9 form, offer letters, employment contracts, Third party contracts signed electronically with audit trail. Not looking to use third party paid tools. This will be integrated with our existing Staffing Accounting System developed in C#, .NET, SQL Server environment. We have the API developed to integrate with google drive. Please note that I9 form requires two signatures Employee and person who is verifying. Functionality is similar to [login to view URL]