IconVault's Promise Visualizer shows promise combinators in action: pick Promise.all, Promise.race, Promise.any, or Promise.allSettled, configure each promise's delay and outcome (resolve or reject), then watch them settle in real time on animated lanes. A timeline shows exactly which promise decided the result and when.

It is the fastest way to internalize the difference between all, race, any, and allSettled, including what happens when one promise rejects. Built for students and interview prep. Free and runs fully in your browser.