I made a small web tool called JSON Excel Tool. It’s 100% browser‑based (WebAssembly + Web Workers), so your files never leave your device. Fast, free, and focused on practical data workflows.

Why

I often switch between JSON/Excel/CSV/SQL/HTML/Markdown and hit issues with nested structures, multi‑sheet exports, and privacy. This tool aims to be “simple for quick tasks, powerful for complex data.”

Highlights• Privacy‑first: No uploads, no server storage—everything runs locally.• 50+ formats: JSON, Excel, CSV, SQL, Markdown, HTML, XML, PDF, PNG, JPEG, etc.• Multi‑sheet export: Nested objects/arrays become extra worksheets with foreign keys.• Advanced flattening: Tweak rules, indentation, minify/pretty‑print before export.• Table tools: Transpose, deduplicate, find/replace, type inference & validation, instant clipboard copy.• NDJSON support: Detects and handles JSON Lines out of the box.• Performance: Smooth previews for Excel files up to ~50MB on modern browsers.

Try it• Home: JSON Excel Tool ↗• JSON → Excel: JSON to Excel ↗• Excel → JSON: Excel to JSON ↗• Docs: Documentation ↗

Feedback is welcome—bug reports and feature requests with sample data/screenshots help a lot: support@exceltojson.online