Hey Product Hunt 👋 The event loop is one of those things every JS developer "knows" until an interviewer asks why a Promise logs before setTimeout(0). [I kept re-learning it from static diagrams and blog posts, and it never fully stuck.] So we built the thing we wished existed: an animated, steppable event loop where you can paste your own code and watch every callback move between the call stack, Web APIs, and the two queues. A few things we're proud of: → Same animation, three depths. Toggle between a kid-friendly story, a developer's mental model, and the actual HTML spec terms. → Step backward, not just forward, so you can rewind to the exact moment something got queued. → A microtask starvation scene that shows how endless promises can freeze timers. Huge credit to Philip Roberts' Loupe, which inspired this years ago. It's free. We'd love to hear which snippet confused you most, so we can add it as an example!

The Event Loop, Visualized

Watch the JS event loop run your code, step by step

Watch the JS event loop run your code, step by step