Build it: Webhooks
An interactive sandbox where you drag real components together, connect them, and run a live traffic simulation to see where the design breaks.
Challenge: Stripe sends webhook events to your endpoint. Things like <code>payment_succeeded</code> and <code>refund.created</code>. Build a webhook receiver that <strong>responds fast</strong> (within 2 to 5 seconds) and does the real work in the background through a queue and workers.