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.
Keep completed contracts paired with signing proof.
Keep signed agreements ready for handoff, with signature certificates or audit trails beside them and a clear note when proof is missing.
Keep signed contracts and signing proof together for review.
Your signed agreements and signing logs land together in the restricted folder you choose, and the owner gets links to both PDFs.