platformIn-browser AI app builder by StackBlitz. You type a prompt, and a working app appears in the browser without any installation or local setup. The whole loop happens in WebContainers, which means the runtime is real Node, not a fake preview. Great for visual prototyping when you want to see something live in sixty seconds and decide whether the idea is worth pursuing further. I'd reach for it to test a hunch fast, then port the work into Cursor or Codex once the shape of the product is clear.