This product was not featured by Product Hunt yet. It will not be visible on their landing page and won't be ranked (cannot win product of the day regardless of upvotes).
Watch JavaScript execute step by step. See the call stack, Web APIs, microtask & task queues, and event loop animate in real time. Finally understand why Promises fire before setTimeout and how async/await actually works. ✦ Breakpoints, step mode, speed control ✦ 20+ examples · Side-by-side comparison · Share via URL ✦ Spec-linked step explanations Free. No signup.
I built JS Visualizer because I spent months explaining the JavaScript event loop to fellow developers — and words never quite worked. Diagrams helped, but they were static. What people needed was to see it move.
So I built a tool where you paste any JS snippet and watch it execute: functions entering the call stack, setTimeout callbacks waiting in Web APIs, Promises resolving through the microtask queue — all animated, all in sync with the line of code being executed.
A few things I'm especially proud of: → The microtask vs. macrotask ordering is precise — it shows exactly why Promise.then() always fires before setTimeout callbacks → Step Explanations link to the ECMAScript spec section for each action → The guided tour walks first-time users through every panel → Everything is shareable via a single URL
It's completely free, no account needed. Just paste code / select any example and hit Run.
Would love your feedback — there's literally a Feedback button in the corner 😄 What examples or features would make this more useful for you?
No comment highlights available yet. Please check back later!
About JS Visualizer on Product Hunt
“Finally understand the JS event loop”
JS Visualizer was submitted on Product Hunt and earned 4 upvotes and 1 comments, placing #85 on the daily leaderboard. Watch JavaScript execute step by step. See the call stack, Web APIs, microtask & task queues, and event loop animate in real time. Finally understand why Promises fire before setTimeout and how async/await actually works. ✦ Breakpoints, step mode, speed control ✦ 20+ examples · Side-by-side comparison · Share via URL ✦ Spec-linked step explanations Free. No signup.
JS Visualizer was featured in Productivity (653.8k followers), Education (78.7k followers) and Developer Tools (514k followers) on Product Hunt. Together, these topics include over 241k products, making this a competitive space to launch in.
Who hunted JS Visualizer?
JS Visualizer was hunted by Supratik Das. A “hunter” on Product Hunt is the community member who submits a product to the platform — uploading the images, the link, and tagging the makers behind it. Hunters typically write the first comment explaining why a product is worth attention, and their followers are notified the moment they post. Around 79% of featured launches on Product Hunt are self-hunted by their makers, but a well-known hunter still acts as a signal of quality to the rest of the community. See the full all-time top hunters leaderboard to discover who is shaping the Product Hunt ecosystem.
Want to see how JS Visualizer stacked up against nearby launches in real time? Check out the live launch dashboard for upvote speed charts, proximity comparisons, and more analytics.
Supratik Das
Hey Product Hunt! 👋
I built JS Visualizer because I spent months explaining the JavaScript event loop to fellow developers — and words never quite worked. Diagrams helped, but they were static. What people needed was to see it move.
So I built a tool where you paste any JS snippet and watch it execute: functions entering the call stack, setTimeout callbacks waiting in Web APIs, Promises resolving through the microtask queue — all animated,
all in sync with the line of code being executed.
A few things I'm especially proud of:
→ The microtask vs. macrotask ordering is precise — it shows exactly why Promise.then() always fires before setTimeout callbacks
→ Step Explanations link to the ECMAScript spec section for each action
→ The guided tour walks first-time users through every panel
→ Everything is shareable via a single URL
It's completely free, no account needed. Just paste code / select any example and hit Run.
Would love your feedback — there's literally a Feedback button in the corner 😄 What examples or features would make this more useful for you?