CSV to Excel, Excel to CSV and JSON converter
Convert CSV to Excel, Excel to CSV, CSV to JSON or JSON to CSV in your browser, with no upload. IDs with leading zeros stay text and formulas never run.
Process locally
Files stay in this browser session. Closing or clearing releases them.
Choose files
CSV, XLSX, JSON, one at a time
Drop files here, or
Adjust settings
Optional: Convert to, Encoding, Delimiter and more
Run
Processes in this browser; cancel at any time
About this tool
Convert CSV to Excel, Excel to CSV, CSV to JSON and JSON to CSV: open a shop or bank export in Excel, save a sheet as CSV for an import form, or hand table data to code as JSON. Product codes and IDs with leading zeros, such as 007, stay text, so nothing is lost on the way.
Everything runs in your browser and the file is never uploaded: one file of up to 10 MB is read and converted on your device. Number columns are stored as numbers in Excel and JSON, formulas are never run, and CSV output starts with a UTF-8 BOM by default so that Excel shows accented and Chinese text correctly.
How to use it
- Choose or drop one CSV, Excel (XLSX) or JSON file. Its first rows appear in the preview so you can check the columns.
- Pick the target format in “Convert to”: Excel (XLSX), CSV or JSON.
- If a CSV looks wrong in the preview, change the “Encoding” (GB18030 for Simplified Chinese files saved by Excel) or the “Delimiter”. For a workbook with several sheets, enter the “Worksheet” name.
- Select Run, then download the converted file. It keeps the original file name with the new extension.
Formats and limits
- Input
- CSV, XLSX, JSON, one at a time
- Output
- XLSX, CSV, JSON
- Size limit
- 10 MB
- Settings
- Convert to (Excel, CSV, JSON); Encoding (UTF-8, GB18030); Delimiter (Comma, Semicolon, Tab, Pipe); First row is header; Worksheet; Store number columns as numbers; UTF-8 BOM; Formula injection protection
- Privacy
- Files stay in the current browser session. No file bytes are uploaded.
- Price
- Free, no sign-up
Common questions
Will IDs and phone numbers keep their leading zeros?
Yes. A column becomes numbers only when every value is a plain number, such as 42, 3.5 or amounts that all have two decimals like 12.50, so 007, 0042, 1,000 or 18-digit ID numbers stay text, and CSV output writes numbers back as they were. Turn off “Store number columns as numbers” to keep every column as text, for example for phone numbers in JSON.
Why does Excel show garbled characters when I open a CSV?
Excel assumes a local encoding for CSV files without a byte order mark. Leave “UTF-8 BOM” on when converting to CSV and Excel reads accented and Chinese text correctly. For a CSV that Excel saved on Chinese Windows, choose GB18030 under “Encoding” before converting.
Can I convert JSON to CSV or Excel?
Yes. A list of objects, one per row, is the usual layout; keys become columns in the order they first appear. A list of rows whose first row is the header, a list of plain values, and an object that holds exactly one such list, like {"data": [...]}, work too. Nested objects and lists are written as JSON text in a single cell.
What happens to formulas, formatting and other sheets?
Formulas are never run: the value Excel saved with the file is used, or the formula text when there is none. Colours, merged cells and charts are not carried over, and only one worksheet is converted. Files with macros are refused. In CSV output, “Formula injection protection” puts an apostrophe before text that starts with =, +, - or @, so a spreadsheet treats it as text.
How large can the file be?
Up to 10 MB, 30 columns and 100,000 rows. Excel files are limited to 50,000 rows, both when reading and when writing.
Is my file uploaded to a server?
No. The conversion runs in your browser, so the file never leaves your device; that makes it safe for bank exports, customer lists and other private data. Closing the page releases the file.
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