Google Drive is Google's file sync app that lets you store all of your files online alongside your Google Docs documents, and keep them synced with all of your devices.
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.