Google Contacts, the address book built into Gmail, lets you keep track of all your contacts, see when you last interacted with them, and more.
Send approved agreements with fields for each signer.
Your signers get the agreement to sign, and you can see the request link and sent status on the case.
Check the approved PDF before inviting the agreement's signers.
Your agreement goes to the right signers in the order you choose, and the case gives its owner a link to the request.