CSV Merger Tool

Merge CSV Files
Into One

Upload multiple CSV files and combine them into a single file — instantly, in your browser.

Upload CSV files or drag and drop them here

Select two or more CSV files · Processed entirely in your browser

Selected files

Your merged file

Download
Files are processed entirely in your browser and are never uploaded to any server.

How it works

Merge CSV files in three steps

Everything runs in your browser. No account, no software, no files leaving your device.

Upload your files

Select two or more CSV files using the upload area, or drag and drop them in.

Review your selection

Remove any files you don't need. The tool checks that all headers match before merging.

Download the result

Click Merge Files and download your combined CSV — one header row, all data rows.

Why use this tool

Fast, private, and simple by design

Most online CSV tools are cluttered with ads, require sign-ups, or upload your data to a server. This one doesn't.

100% Private

Your data never leaves your browser. No uploads, no cloud storage, no logs.

Instant Results

Processing happens locally at full browser speed. Even large files merge in seconds.

Single Header Row

Headers from the first file are kept once. Duplicate headers from other files are removed automatically.

Completely Free

No account required. No file size limits enforced by a paywall. Just the tool.

FAQ

Frequently asked questions

Upload two or more CSV files using the tool above. Once your files are selected, click "Merge Files." The tool combines all the data rows into a single CSV, preserving just one header row, and gives you a download link for the result.
Yes, completely free. No account, no subscription, no file size paywall. The tool runs entirely in your browser, which is why there are no server costs to pass on.
No. All processing is handled locally in your browser using the Web File API. Nothing is sent to any server, and there are no logs of your files or their contents. This makes the tool safe for sensitive or confidential data.
The tool compares the header row of every file before merging. If any file has different column names or a different column order, it will show a clear error message telling you which file doesn't match. All headers must be identical for the merge to proceed.
Yes. The tool processes files in-browser and handles most typical CSV sizes well. Very large files may take a moment depending on your device, but there is no server-side size limit. Performance depends on the total combined size of your input files.
The output file is named based on how many files you merged. For example, merging three files produces merged-3-files.csv. You can rename the file after downloading it.