Hey HN! I built FormatLab because I was tired of spending way too many hours writing one-off Python scripts or Excel formulas/models for simple tasks..

FormatLab runs 100% in your browser—no backend, no uploads, no accounts. Process sensitive data without worrying about privacy.

Tools include: CSV viewer/merge/split/diff, JSON formatter/validator/tree-viewer, Excel converter, and more.

Tech stack: Next.js 15, TypeScript, client-side file processing with Papa Parse and ExcelJS.

Would love feedback on the UX and any tools you'd want to see added!