OfficeUtils
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Merge CSV

Combine multiple CSV files with the same columns into one, locally.

Files are processed on your device and are never uploaded.

Files are processed on your device and are never uploaded.

By using this tool, you agree to our Terms and Privacy Policy.

How it works
  1. Add your file(s) above.
  2. Merge CSV runs instantly in your browser. Nothing leaves your device.
  3. Download the result. That's it.

Don't take our word for it. Open your browser's DevTools (F12), click the Network tab, and run the tool. It stays empty, because the code that processes your file shipped to your browser along with this page — there's no server for it to travel to.

Frequently asked questions
What if the files have different columns?
The merge stops with a clear error naming the mismatched file, instead of silently combining columns that do not line up.
Are my files uploaded to a server?
No. Everything runs locally in your browser. You can verify it yourself: open DevTools and watch the Network tab while the tool runs. It stays empty the whole time. This also means the tools keep working offline once the page has loaded.
What are the free limits?
Free covers every tool at full quality with no watermark and no signup: single jobs, up to 3 files and 25 MB total. Pro adds batch queues (up to 50 files), jobs up to 200 MB, tool chains and saved presets, all from one license that also unlocks the browser extension.