Do your clients need to sign an estimate or invoice before proceeding with payment? Sprout Invoices has created an incredibly powerful WP E-Signature / Invoice & Estimate integration.
Gravity Flow is a robust workflow service that connects to Gravity Forms. Easily integrate advanced signing workflows using Gravity Flow and Gravity Forms.
Automatically tag or subscribe signers of a document to an Active Campaign email list. You can even trigger events, email campaigns and workflows in Active Campaign by giving a signer a tag when they electronically sign your contract.