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convertexa

CSV → XLSX

CSV to XLSX converter

convertexa converts CSV files to XLSX locally in your browser using a dedicated data engine. Nothing is uploaded: the file is read, converted and handed straight back to you as a download.

  • Free, no sign-up
  • Nothing is uploaded
  • Works offline
Quality
Re-encoded
Runs
In your browser
Max input
25 MB
Status
stable

Drop a file to convert

Everything happens on your device — nothing is uploaded.

or paste with Ctrl+V

How to convert CSV to XLSX

  1. 1 Drop your CSV file here.
  2. 2 Choose the output format.
  3. 3 Convert and download the result.

About CSV and XLSX

CSV is plain text; the first row is treated as the header.

XLSX workbooks are read and written with ExcelJS.

CSV files are read by the convertexa engine that ships with this page, so the conversion is identical whether you use this tool or the general converter. The output is produced with the same codec settings for every visitor, which means the same input always produces the same result.

Limitations

  • Only the first sheet is produced; CSV has no notion of sheets.

Frequently asked questions

How do I convert a CSV file to XLSX?

Add your CSV file to the box above. convertexa detects the format from the file content, applies the CSV to XLSX conversion and gives you the result to download. The whole operation runs inside your browser.

Are my CSV files uploaded anywhere?

No. The conversion runs in a sandboxed worker on your own device. Your file never leaves the browser, and nothing is stored on a server.

Is the CSV to XLSX conversion lossless?

No. XLSX is a re-encoded format, so some data is discarded to reach the target format. CSV is plain text; the first row is treated as the header.

Is there a size limit?

For reliable results keep the input under 25 MB. Very large files run out of memory in the browser rather than failing quietly.

Which browsers are supported?

Any current version of Chrome, Edge, Firefox or Safari on a desktop. The conversion engines need WebAssembly and Web Workers, both of which are standard since 2018.