CSV & Excel to JSON
Convert spreadsheets and CSV files to clean JSON instantly. Type inference, multi-sheet Excel support, zero uploads.
Paste CSV or upload a file
100% local — your data never leaves your browser. Open DevTools (F12 → Network) to verify zero uploads.
CSV & Excel to JSON Converter — Free, Private, No Upload
Convert CSV, TSV, and Excel (.xlsx, .xls) files to clean, formatted JSON entirely in your browser. Supports custom delimiters, type inference (numbers, booleans, nulls), and pretty-printed output. Your data never leaves your device.
Smart Type Inference
Numbers, booleans (true/false), and null/empty values are automatically converted to their correct JSON types. "42" becomes 42, "true" becomes true, and empty cells become null. Toggle off to keep everything as strings.
CSV, TSV & Excel Support
Handles comma-separated (CSV), tab-separated (TSV), semicolon-separated, and Excel (.xlsx / .xls) files. The delimiter is auto-detected from the file extension, or you can override it manually.
100% Private — No Upload
CSV and spreadsheet files often contain sensitive business data. This tool processes everything locally using SheetJS inside your browser. Zero bytes are transmitted to any server at any point.
How it Works
Upload a CSV, TSV, or Excel file — or paste CSV text directly into the input area.
Choose your delimiter and toggle type inference if needed.
The JSON output appears instantly as you type or upload.
Copy the JSON to clipboard or download it as a .json file.
Protocol
SheetJS (Browser)
Data Cloud Sync
None — Zero Transmission
Residency
Browser RAM Only
Frequently Asked Questions
Q: What file formats are supported?
CSV (.csv), TSV (.tsv), semicolon-separated, and Excel (.xlsx, .xls). You can also paste raw CSV text directly into the input area.
Q: What is type inference?
When enabled, numbers become numbers, "true"/"false" become booleans, and empty cells become null. When disabled, every value is a string.
Q: How are column headers handled?
The first row is used as JSON object keys. Each subsequent row becomes a JSON object with those keys.
Q: Can I convert multiple Excel sheets?
Yes. A sheet selector appears when you upload a multi-sheet workbook. Each sheet produces its own JSON array.
Q: Is my data uploaded to your servers?
No. SheetJS reads your file entirely in browser memory. Nothing is transmitted externally.
Q: What is the maximum file size?
No server-side limit. Very large files (50MB+) may be slow depending on your device RAM.
Privacy Guarantee
Zero Data Retention Policy
All document processing happens inside your browser sandbox using WebAssembly. No files are ever uploaded or stored.