Service agreements, talent releases, and addendums go out for signature in your agency's own name. Your letterhead, your fonts, your colours. The client sees you, not a signing vendor.
The document itself is built from the engagement you already agreed: the same service lines, the same numbers, so the paperwork matches what was actually discussed.
Unsigned agreements chase themselves. Reminders go out automatically, and anything approaching its expiry is flagged before it becomes a problem.
No separate signing product to buy, and no second login for you or your client to remember.