FeaturePeek is a web application that lets designers leave feedback on in-progress developer implementations. Many tools today specialize in design prototyping and collaboration, but fall short after the developer-handoff stage. FeaturePeek leverages on-demand feature environments, spinning up isolated environments automatically for every pull request – allowing the collection of feedback pre-merge. Team members can post annotations and comments directly on the implementation via a minimal UI overlay, and send actionable items to the bug-tracking software of their choice.