How to use
- Open a file.
- Choose the output format and options (sheet, delimiter, JSON as array of objects or arrays).
- Convert and download.
Worked example
id,name,qty with 000123,Ann,42 converted to XLSX and then to JSON with typed values gives {"id":"000123","name":"Ann","qty":42}: the ID keeps its zeros as text and 42 becomes a number. [{"name":"Ann","address":{"city":"Oslo"}}] flattens to the CSV columns name,address.city and rebuilds the same JSON.
Supported formats and limits
| Input | CSV, TSV, XLSX, XLS, ODS, JSON |
|---|---|
| Output | CSV, TSV, XLSX, JSON |
| Limits | Up to 100 MB. |
| Engine | SheetJS Community Edition + Papa Parse; dot-path flattening for nested JSON |
Limitations
- Formulas are exported as their last calculated values; formatting and charts are not converted.
- XLS and ODS can be read but not written; output is CSV, TSV, XLSX or JSON.
- Arrays in JSON become numbered columns (tags.0, tags.1).
Questions
Will IDs such as 000123 keep their leading zeros?
Yes. Only values written as plain canonical numbers (such as 42 or -1.5) become numeric cells or JSON numbers; 000123 stays text. You can also write every XLSX cell as text, or turn off typed JSON values.
Which conversions are supported?
Input: CSV, TSV, delimited text, XLSX, XLSM, XLS, ODS, JSON and JSON Lines. Output: CSV, TSV, XLSX and JSON as an array of objects, an array of arrays or JSON Lines.
What happens to workbooks with several sheets?
The first sheet is converted unless you choose another. With all sheets selected, XLSX output keeps them as sheets in one workbook, and CSV or JSON output gives one file per sheet.
What is lost in conversion?
Formulas become their last calculated values, and formatting, charts and comments are dropped. Spreadsheet dates are written as text such as 2026-03-04.
Guides
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