CSV to Excel Converter: Convert CSV to XLSX Free
Convert a CSV file into a proper .xlsx workbook and download it. Free CSV-to-Excel converter that avoids the encoding and delimiter problems of a plain rename.
Runs in your browser. Nothing is uploaded.
How it works
- Step 1: Choose your spreadsheetPick a file from your device or drag it onto the page. It is read locally. The file is never transmitted.
- Step 2: Pick the sheet and columnsSet the options you want and run it. Progress is shown as your browser works through the file.
- Step 3: Download the resultSave the finished file straight back to your device. Nothing is retained after you close the tab.
About this tool
- Runs in your browser. All processing happens locally in this tab using JavaScript.
- No uploads. Your data is never sent to a server. There is no server to send it to.
- Works offline. Once the page has loaded you can disconnect and keep working.
- Unlimited & free. No usage caps, no paywall, no file size tiers.
Choose a spreadsheet
What happens to your data
The same questions a security review would ask, answered plainly.
- Read via
- The browser File API, on your device
- Held in
- Your browser tab's memory for as long as it is open
- Stored
- Nothing. No cookies, no database, no server-side copy
- Transmitted
- Nothing leaves your device
- Retained after you close the tab
- Nothing
- Works offline
- Yes, once the page has loaded
Why use this tool
What you get here that a server-side alternative cannot offer.
Your data never leaves the tab
There is no upload step and no server to receive one. The page loads once, then all work on your spreadsheets happens in local JavaScript.
No caps or paywalls
No daily limits, no per-file ceilings imposed by a server tier, no watermarks, and no account. The practical limit is your own device's memory.
Frequently asked questions
Is my CSV uploaded to a server?
No. Everything runs locally in your browser using JavaScript. Your data is never uploaded to a server, and nothing is stored or logged.
Why not just rename the file to .xlsx?
They are different formats. CSV is plain text, XLSX is a zipped XML package. Renaming produces a file Excel refuses to open; a real conversion is required.
Will long numbers keep their leading zeros?
Values that look numeric are written as numbers, so IDs and postcodes can lose leading zeros. Check those columns after converting if they matter.
Is there a file size limit?
There is no limit imposed by us, because there is no server tier to enforce one. The real constraint is your device's available memory, since the whole file is held in RAM while it is processed. Very large files are slower on phones than on a laptop.
Does it work offline?
Yes, once the page has loaded. The code that does the work is already in your browser at that point, so you can disconnect and keep using it. Reloading the page while offline needs the browser cache to still hold it.
Do I need to create an account?
No. There is no sign-up, no email, and no usage tracking tied to an identity. The tool works the first time you open it.