Developer builds free in-browser debugger to fix Next.js hydration errors

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A developer frustrated by recurring Next.js hydration errors, including the cryptic React Error 418, has built a free, privacy-first diagnostic tool to help others resolve them faster. The tool accepts raw error logs or JSX snippets and identifies the root cause, whether it stems from dynamic timestamps, invalid HTML nesting, browser extension interference, or client-only storage reads. All analysis runs entirely in the browser, meaning no code is sent to external servers. The project was prompted after the author spent nearly two hours tracing a production error to a browser extension injecting attributes into the DOM before React could mount. The tool also provides verified before-and-after code fixes for the five most common hydration pitfalls in Next.js App Router and React 18/19 SSR projects.

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