Live React sandbox check

Generated React usually looks plausible: imports that read correctly, hooks in a sensible order, a component that returns something. None of that is evidence. The failures that matter only exist at runtime — an import path that does not resolve, a prop that arrives undefined because nothing passed it, a hook placed after an early return.

A live mount turns each of those into a message. That is the whole argument for running the code rather than reading it: the browser is the only reviewer that cannot be persuaded by confident syntax.

A blank preview has three plausible causes — a compile error, a runtime exception, or a component that legitimately renders nothing — and the console distinguishes them. Switch to the broken preset to see what a first-render failure looks like: the preview shows the overlay and the console names the line.

Warnings are worth reading too. A missing key, a state update during render or a dependency array that changes every render will not stop the component mounting now, and all three will misbehave once real data arrives.

The sandbox has no real props, no authenticated user, no API and no server data. A clean run proves the component compiles and survives its own default state, not that the feature works. Logic, data handling and anything security-adjacent still belong to the console and a human reviewer.

And unlike the rest of the toolbox, this tool is not offline: Sandpack sends the files to CodeSandbox's bundler to compile and run them. Never paste secrets, customer data or private source you would not hand to a third party.