> For the complete documentation index, see [llms.txt](https://doc.duaer.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://doc.duaer.com/tools/csv-to-excel.md).

# CSV to Excel converter (free, no upload)

A free Duaer tool that turns CSV into .xlsx in your browser. It detects UTF-8 or GBK, keeps long IDs as text, and never uploads the file.

Interactive converter (runs in the browser, no upload): https://doc.duaer.com/tools/csv-to-excel/

## How to use it

1. Drop the file into the box above, or click "choose a file".
2. Check the preview to make sure rows and columns line up.
3. Click "Download .xlsx".
4. Pick several CSV files at once to get one .xlsx with a sheet per file.

## Conversion rules

- Encoding: UTF-8 first, then GBK if UTF-8 fails. CSV exported from older Excel or many Chinese business systems is GBK.
- Delimiter: comma, tab, semicolon, or pipe, detected automatically.
- Numbers: plain numbers become numeric cells you can sum. Codes with a leading zero and numbers longer than 15 digits (national IDs, card numbers, order numbers) stay text.
- To keep every cell as text, tick "Write every cell as text".

## Automate it in Duaer

Converting the same CSV every day? In Duaer, read it with [Extract from File](/integrations/builtin/core-nodes/duaer-nodes-base.extractfromfile.md) › Extract From CSV, then write it with [Convert to File](/integrations/builtin/core-nodes/duaer-nodes-base.converttofile.md) › Convert to XLSX. For GBK files, use Extract From Text File (Options › File Encoding: gbk) and split rows as in [Parse CSV in a Code node](/snippets/parse-csv-in-code-node.md).
## Questions

### Why does Excel show garbled text for my CSV?

Excel often opens UTF-8 CSV with the system code page. Convert it to .xlsx with the Duaer CSV to Excel tool and the encoding problem goes away.

### Why do long IDs turn into 1.10101E+17?

Excel cuts numbers past 15 digits. The Duaer converter keeps longer numbers as text, so the .xlsx shows the full value.

### Is there a file size limit?

Duaer sets no limit; your browser memory does. CSV files of tens of megabytes usually work.

## Related

- [Free file converters from Duaer](https://doc.duaer.com/tools.md)
- [Excel to CSV converter (UTF-8, no upload)](https://doc.duaer.com/tools/excel-to-csv.md)
- [JSON to CSV converter (nested JSON flattened)](https://doc.duaer.com/tools/json-to-csv.md)
- [CSV to JSON converter (free, no upload)](https://doc.duaer.com/tools/csv-to-json.md)
- [Merge several Excel files into one sheet with Duaer](https://doc.duaer.com/tasks/merge-excel-files.md)
- [Parse CSV text in Duaer, including GBK files](https://doc.duaer.com/snippets/parse-csv-in-code-node.md)