Merge CSV files
Monthly exports, per-region reports, one file per client — anything that arrives split up eventually has to be joined back together. This stacks your files into one, keeps a single header at the top, and can align columns by name when the files don't share the same column order.
How to use it
- Choose two or more CSV files. They're merged in the order listed.
- Decide whether to match columns by header name — useful when the files have the same columns in a different order.
- Click Merge and download the combined file.
Questions
Is my file uploaded anywhere?
No. This page contains the whole tool — the JavaScript that does the work runs inside your browser tab, on your own machine. There is no server to upload to. You can confirm it yourself: open your browser's developer tools, switch to the Network tab, and run the tool. You will not see your file go anywhere. You can also disconnect from the internet after the page loads and it will still work.
What if my files have different columns?
With column matching on, the merged file contains the union of all columns found, and any file missing a column simply gets an empty cell there. With it off, rows are stacked positionally and the first file's header is used — faster, but only correct if every file has identical columns in identical order.
Can I control the order files are merged in?
Yes. Files merge top to bottom in the order shown after you add them. Remove one with the × and add it again to move it to the end.