Retrotime is a very simple and low feature sticky note app to help run simple retrospectives.
On the other hand, TeamRetro is an enterprise-ready tool specifically built for agile retrospective and health check to improves meeting value, safety, and actionable outcomes. You can get insights for improvement and has an easy to use and reliable interface that allows retrospectives to run smoothly. Beyond simple brainstorming, TeamRetro also captures data such as team sentiment, action item tracking, team health as well as other common agile metrics. The best thing about TeamRetro is that it is simple for people to use.