Upload your files
Select two or more CSV files using the upload area, or drag and drop them in.
CSV Merger
Upload multiple CSV files and combine them into a single file — instantly, in your browser.
Upload CSV files or drag and drop them here
In your browser · Up to 200 MB per file (50+ MB may feel slow)
Selected files
Remove All
Results
Files are processed entirely in your browser and are never uploaded to any server.
How it works
How to merge CSV files online
Everything runs in your browser. No account, no software, no files leaving your device.
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 paywall — generous in-browser limits (200 MB per file, same as our other CSV tools).
FAQ
Frequently asked questions
Upload two or more CSV files, then click Merge Files. The tool combines all data rows into one CSV with a single header row and gives you a download link.
Yes. Merging runs in your browser. The result is standard CSV and works in Excel, Google Sheets, and other tools.
The tool checks headers before merging. If any file has different column names or order, it shows an error and which file failed. All headers must match to proceed.
Yes. Processing runs locally in your browser. Nothing is uploaded or stored.
Yes, within reason. Each file can be up to about 200 MB (browser memory permitting). Files over 50 MB may take longer to read and merge. Everything still runs locally — there is no server upload.
By number of files merged: e.g.
merged-3-files.csv. You can rename after downloading.