GoRetro - a free retrospective tool for your Agile sprints
Neatro - Neatro is the online Agile retrospective platform designed to help teams improve continuously.
Retroly - A fun simple tool for agile retrospectives
Retrospect.team - Easily conduct end of sprint and project retrospectives with everyone on your team no matter their location.
Parabol - Agile Meeting Co-Pilot
Outro - A new take on retrospectives for progressive teams