CSV to Excel Converter — .xlsx
Convert CSV to a real Excel .xlsx file in your browser: delimiter auto-detection, numbers auto-typed, headers kept. No upload, no signup. No upload — runs 100% in your browser
or click to browse
How to use this tool
- Paste or drop your input above.
- The tool processes it locally — usually instantly.
- Copy the output or download the result.
A real .xlsx, built on your machine
This converter produces a genuine Excel workbook — not a CSV renamed to .xlsx, which Excel only opens out of politeness. The sheet gets proper cell structure, the first row stays as your header, and the whole job runs locally with SheetJS, the open-source spreadsheet library that works in the browser.
Where the numbers land
Cells that unambiguously look numeric (plain integers and decimals) are written as actual numbers you can SUM and chart. Values that could be numbers but shouldn't — ZIP codes with leading zeros, phone numbers, IDs like 007 — stay text so Excel doesn't silently corrupt them. Dates stay text as well, because date parsing depends on your locale and Excel's guesses have eaten more data than any other office feature.
Delimiter detection
Drop the file or paste its content and the first line is inspected for the separator: comma, semicolon, tab or pipe. European exports that use decimal commas and semicolon separators work without any settings. Every row of the CSV lands in the sheet, in order, including quoted fields containing commas and line breaks.
Frequently Asked Questions
Are my files uploaded to a server?
No. Everything on this page runs inside your browser using JavaScript and WebAssembly. Your file never leaves your device — you can even disconnect from the internet after the page loads and the tool still works.
Will my ZIP codes and IDs keep their leading zeros?
Yes — only unambiguous plain numbers become numeric cells. Anything that would change when interpreted as a number is stored as text.
Does the .xlsx keep formulas, colors or macros?
CSV has none of those, so there is nothing to keep — the workbook contains exactly the grid of values from your CSV.
Can I convert several CSVs into one workbook?
One CSV per run, one sheet. Convert each file, or merge the CSVs first and convert the result.