# CSV to Excel Converter: CSV to XLSX, No Upload | Dedupely

> Convert CSV to Excel (XLSX or XLS) in your browser. ZIP codes keep their zeros, long IDs stay whole and accents survive. Free, and your file is never uploaded.

- URL: https://dedupe.ly/tools/csv-to-excel
- Section: tools
- Site index: https://dedupe.ly/llms.txt
- Any page: append `.md` to its URL for this plain-text form

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## Convert CSV to Excel in your browser

ZIP codes keep their zeros and long IDs stay whole.
[Use in Claude](https://claude.ai/customize/connectors?modal=add-custom-connector&connectorName=Dedupely%20free%20tools&connectorUrl=https%3A%2F%2Fdedupe.ly%2Ftools%2Fmcp)
CSV file
Or paste rows here
First row is a header
Convert
Free for 10 runs a day.

### Every ZIP code keeps its zero

Excel reads 02134 as a number and drops the zero. Long IDs turn into 1.21E+10. Saving back to CSV makes the loss permanent.
**This converter stores those columns as text in the Excel file.**

### Semicolons and accents open right

European exports separate columns with semicolons. Excel puts each whole row in column A. José opens as José.
**The separator is detected and every name reaches Excel spelled right.**

### Use it from a script or an AI agent

[Use in Claude](https://claude.ai/customize/connectors?modal=add-custom-connector&connectorName=Dedupely%20free%20tools&connectorUrl=https%3A%2F%2Fdedupe.ly%2Ftools%2Fmcp)
MCP https://dedupe.ly/tools/mcp every free tool in one connector (this one: csv_to_excel)
POST https://dedupe.ly/tools/api/csv-to-excel
{ "csv": "ZIP,Phone\n02134,+12125550123", "format": "xlsx" }
Docs https://dedupe.ly/tools/api/openapi.json
[OpenAPI document](https://dedupe.ly/tools/api/openapi.json) ·
[API index](https://dedupe.ly/tools/api) ·
[llms.txt](https://dedupe.ly/llms.txt)

### Questions about converting CSV to Excel

How do I convert CSV to Excel?
Choose the CSV file or paste its rows, pick .xlsx or .xls and press Convert. The Excel file downloads straight away.
Is my CSV uploaded?
No. The conversion runs in your browser and the file never leaves your computer.
Why does Excel remove leading zeros?
Excel reads a column of digits as a number, and a number has no leading zero. This converter writes any value that starts with 0 as text, so 02134 stays 02134.
Why do long numbers show as E+?
Excel keeps 15 digits of a number and shows the rest in scientific notation. Values longer than 15 digits, or starting with a plus sign, are written as text and stay whole.
My CSV uses semicolons. Will it split into columns?
Yes. Comma, semicolon and tab files are detected and split into columns.
Can I get an .xls file instead of .xlsx?
Yes. Pick .xls for Excel 97 to 2003. An .xls sheet holds 65,536 rows and 256 columns at most.
Will dates or codes change?
No. Dates and codes such as 3-4 or MAR1 are written exactly as they appear in the CSV.
Can I keep every cell as text?
Yes. Tick the option to keep numbers as text too, and Excel shows every cell exactly as the CSV has it.
Is it free?
Yes. Ten conversions a day, free.

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