---
title: "CSV to Excel (XLSX) — Free, Private, No Upload | Compress Pro"
description: "Convert CSV files to Excel XLSX right in your browser — delimiters auto-detected, numbers typed, nothing uploaded. Free, no accounts, no limits."
canonical: https://compress-pro.com/csv-to-xlsx
---

# Convert CSV to XLSX.

> CSV turned into a real Excel workbook — on your device.

Convert CSV files to real Excel workbooks entirely in your browser — **delimiters auto-detected (comma, semicolon, tab), numbers typed as numbers, text kept as text**. Drop the .csv, download the .xlsx. Nothing is ever uploaded.

**No uploads · No ads · Free & open source.**

## How it works

1. Drop files anywhere on the page, click to browse, or paste with Ctrl/⌘ + V.
2. Pick a quality or preset — or set an exact target size and let the tool find it.
3. Compress, compare before/after, and download — individually or as a ZIP.

## What a proper conversion gets right

CSV has no types — everything is text until something interprets it. This tool re-types pure numbers as numeric cells so sums and charts work immediately, while anything ambiguous stays text: date-looking strings, fractions like 1/2 and codes like MARCH1 are NOT silently turned into dates, the classic spreadsheet-import disaster. Quoted fields, embedded commas and multi-line cells all survive; semicolon and tab files (European Excel exports) are detected automatically.

## The whole family on one tab

This page is the front door of the data tab: drop any of the four formats and the direction follows the file — [XLSX back to CSV](https://compress-pro.com/xlsx-to-csv), [JSON to YAML](https://compress-pro.com/json-to-yaml) and [YAML to JSON](https://compress-pro.com/yaml-to-json) all run through the same engine. Batch a mixed folder and every file comes back converted the right way.

## Under the hood

Spreadsheets are read and written by SheetJS — the open-source library behind most of the JavaScript spreadsheet world — and the JSON/YAML side runs on the standard `yaml` parser, both loaded on demand in your browser. Your data never leaves the device: no upload, no server-side copy, and the tools keep working offline once loaded. For business and personal data that is not a nice-to-have — it is the point.

## Frequently asked questions

### Will my numbers and dates survive?

Numbers become real numeric cells. Date-looking strings deliberately stay text — automatic date guessing is how "1/2" becomes January 2nd in other tools. Format columns as dates in Excel afterwards if you need them typed.

### Does it handle semicolon CSVs from European Excel?

Yes — the delimiter is sniffed per file, so comma, semicolon and tab files all convert correctly, decimal commas included.

### Is there a size limit?

No hard limit — typical exports convert instantly. Very large files (tens of MB) take a few seconds since everything runs on your own machine.

### Is my data uploaded?

No. The conversion runs entirely in your browser — the server only delivers this page. Spreadsheets full of names, prices or personal data never leave your device. Want proof? Run one file through, switch your connection off, and run another — it still works.

## Related tools

- [Convert XLSX to CSV](https://compress-pro.com/xlsx-to-csv)
- [Convert JSON to YAML](https://compress-pro.com/json-to-yaml)
- [Zip & Unzip files](https://compress-pro.com/zip-files)

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Part of [Compress Pro](https://compress-pro.com/) — every tool page has a markdown twin at `<page url>.md`. Full tool index: [llms.txt](https://compress-pro.com/llms.txt)