← All tools Free tool · Runs in your browser

CSV Merger

Many CSVs in, one clean CSV out.

  1. Load two or more CSVs
  2. Pick how headers combine
  3. Download merged.csv

Runs in your browser. Nothing you load here is uploaded or stored.

Step 1

Load your CSVs

The first file in the list sets the column order. Drag files to reorder, or use the arrow buttons.

Files to merge, in order

    No files loaded yet.

    Step 2

    Choose how headers combine

    Any difference stops the merge and names the first mismatch per file.
    Step 3

    Preview and download

    Load a file to see a preview.

    Exports from different months, branches, or systems rarely share an identical header. The merger shows you exactly how each file's columns differ from the first file's before anything is combined, so the choice between strict, union and mapping is an informed one.

    Limits

    • Up to 500,000 rows or 100 MB across all files; past that it stops with a message.
    • The first file in the list sets the column order and, in mapping mode, the target header.
    • Output is UTF-8 with the first file's delimiter; tick "Excel-friendly (add BOM)" if Excel shows accents wrongly.

    Other free tools