Trello is a team collaboration tool that lets you organize anything and everything to keep your projects on task.
Your reviewer gets the current proof and a clear decision deadline by email when a card is ready for review.
Your reviewer sees the current image or PDF proof link and revision on the task before deciding.
Your approval task shows whether the reviewer can open the current proof before the due date, with a request for a corrected link when needed.
Your campaign owners see a blocker on the task when an asset reaches Ready for review without a named reviewer.