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ToolSuite
CSV & Spreadsheet Tools

CSV Merger

Append one CSV to another, checking that the columns match first.

Aligns the second file by column position instead of by name.

Processed in your browser

Fill in the form and press “Merge files” to see the result here.

How to use it

  1. 1Paste your CSV, or open the file in a text editor and copy it in.
  2. 2Adjust the delimiter and header options if the preview looks wrong.
  3. 3Adjust the options if you need something other than the defaults.
  4. 4Download the result, or copy it straight back into your spreadsheet.

About the CSV Merger

The column names are compared before merging, and a mismatch is reported with both header rows. Silently appending files with different columns is how data ends up in the wrong field.

The header of the first file is used for the result, and the second file’s header row is dropped.

Questions people ask

Is your data uploaded to a server?

No. This tool runs entirely in your browser using standard web APIs, so your data never leaves your device. You can confirm it by opening your browser's network panel while the tool runs, or by disconnecting from the internet after the page has loaded.

Is it free, and do I need an account?

Yes, it is free, and there is no account, no sign-up and no watermark on the result. The project is funded by optional donations.