Hey Product Hunt! 👋 I’m **Jin**, the solo maker behind **[ToolGenius.app](https://toolgenius.app)**. ### Why I built it I often bounce between CSV, JSON and Excel files when testing APIs or debugging data pipelines. Every “free” converter I found either uploads my data to a server, caps file size, or ambushes me with ads. So I set out to build a **privacy-first, zero-friction converter** that runs entirely in your browser. ### What’s new / unique * **100 % client-side** – no uploads, so sensitive data never leaves your machine. * **Blazing-fast round-trip** CSV ↔ JSON (and soon XLSX, TSV, YAML). * **Open-source core** under MIT; you can self-host or contribute on GitHub. * Handles multi-MB files via streaming, yet the UI stays < 50 KB and ad-free. ### What I’m most proud of Seeing folks drop a huge CSV, click **Convert**, and watch results appear in milliseconds—then realizing nothing ever touched a server. That “wow, it’s really local!” moment is priceless. ### I’d love your feedback * Does it cover your day-to-day data pain points? * Which format should I add next? * Anything in the UX that slows you down? Thanks for checking it out—your comments and upvotes mean the world! 🚀

ToolGenius - One-click CSV ↔ JSON conversion — secure, open-source & free

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