FileopiaCSV / JSON / Excel Converter
Convert between CSV, TSV, JSON, Excel (XLSX/XLS) and ODS in your browser. Handles nested JSON, multi-sheet Excel and Unicode.
- Upload
- Options
- Download
- ✓ 100% free
- ✓ No sign-up
- ✓ No limits
- 🔒 Files never leave your device
How to: Data Converter
- Select CSV, JSON or Excel files.
- Pick the output format.
- Download.
Data moves between spreadsheets, databases, APIs and scripts in different formats. One converter handles them all locally, so customer lists and financial data stay private.
Common uses
- Prepare spreadsheet data for an API or app.
- Open JSON exports in Excel.
- Convert ODS files from LibreOffice.
Tips for best results
- UTF-8 is used throughout, so accents and non-Latin scripts are kept.
Choosing the right format
CSV is the simplest and most widely accepted for imports. TSV avoids problems when data contains commas. JSON suits APIs and apps, especially with nested data. XLSX and ODS keep multiple sheets and proper data types for people working in spreadsheets.
Encoding and special characters
All conversions use UTF-8, so names like José, Müller or 東京 survive the round trip. When exporting CSV for Excel, a byte order mark is added so characters display correctly.
Why use Fileopia for Data Converter?
| Fileopia | Typical upload-based sites | |
|---|---|---|
| Files uploaded to a server | No – processed on your device | Yes |
| Sign-up required | Never | Often for bigger jobs |
| Hourly / daily task limits | None | Common on free plans |
| Watermark on output | Never | Sometimes |
| Works offline after loading | Yes, for most tools | No |
Your files never leave your device
Data Converter runs entirely in your browser using JavaScript and WebAssembly. Your files are read from your disk into this tab, processed in memory and saved straight back to your downloads folder – they are never uploaded to Fileopia or any third party.
- Test it yourself: once this page has loaded, switch off Wi‑Fi or mobile data and run the tool – it keeps working.
- Check the network: open your browser’s developer tools (F12 → Network) while processing; you will see no file upload requests.
- Nothing to delete: close the tab and the data is gone – there is no server copy, no retention period and no account.
Frequently asked questions
Is my data uploaded?
No. Spreadsheets and JSON are parsed in your browser and never sent to a server.
Can it handle large files?
Yes, files with hundreds of thousands of rows work on most computers.
Is Data Converter really free?
Yes. Every tool on Fileopia is 100% free with no file limits, no sign-up and no watermarks. The site is supported by unobtrusive ads.
Are my files uploaded to a server?
No. Fileopia processes your files directly in your browser using JavaScript. Your documents never leave your device, so they stay completely private.
Does it work on mobile?
Yes. Fileopia works in any modern browser on Android, iPhone, iPad, Windows, Mac and Linux.