Merge CSV Files
Merge together two or more CSV files. Runs entirely in your browser, so your data never leaves your device.
Drop a file here, or click to browse
Files never leave your device
Drop a file here, or click to browse
Files never leave your device
Output
The result appears here as you type.
How to use Merge CSV Files
- 1. Add your CSV files. Drag two or more .csv files onto the drop zone or pick them with the browse button. They are combined in the order listed, so add them in the sequence you want.
- 2. Handle repeated headers. If every file starts with the same column row, tick Files share a header (keep only the first). The merged output then has one header at the top instead of a header buried between each batch of rows.
- 3. Download the combined file. Click download to save a single CSV containing all rows from every input. Open it in your spreadsheet or feed it to the next stage of your pipeline.
When to use Merge CSV Files
Merge CSV Files concatenates multiple exports into one file, with the common repeated-header problem handled for you. It exists because most systems export data in chunks, per month, per region or per page, while most analysis wants everything in a single table.
- Combining monthly exports. Your accounting system emits january.csv, february.csv and so on. Merge the year's files with the shared-header option on and get one clean table ready for a pivot.
- Stitching paginated API dumps. A script saved an API's results as page-001.csv through page-040.csv. Rather than looping cat and tail in the shell, drop all forty files here and download the union.
- Consolidating survey batches. Responses collected by different team members live in separate files with identical columns. Merging them produces the single dataset your analysis notebook actually expects.
- Preparing one upload from many sources. A CRM import accepts exactly one file. Combine the exports from each regional office first so the whole customer list goes up in a single pass.
Examples
Stack two exports
Input
january.csv + february.csv
Output
One CSV with January's header and both files' rows.
About the Merge CSV Files tool
Merge CSV Files is a free online tool that works entirely inside your web browser. Merge together two or more CSV files. Because the processing happens on your own device, nothing you enter is uploaded, logged or stored anywhere.
This page is one of 133 CSV utilities on EditSafely. Each one does a single job well, and all of them follow the same rule: your input stays on your machine.
You can shape the output with the Files share a header (keep only the first) setting, and the result refreshes the moment you change it. The finished file is put together in browser memory and saved with the Download button, so it never touches a server on the way to your disk. A worked example further down the page shows exactly what the tool produces for a real input.
Because nothing leaves your device, the tool is suitable for sensitive content such as internal documents, credentials or customer data. It also responds instantly, since every keystroke is handled on your own machine rather than by a remote API.
Frequently asked questions
Does Merge CSV Files cost anything?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Are my files uploaded to a server?
No data leaves your device. The whole tool is JavaScript that runs inside your browser tab, so there is no upload, no server-side processing and no log of what you did. If you disconnect from the internet after the page loads, it keeps working.
Which files does Merge CSV Files accept?
It accepts CSV files and text/csv. There is no file size cap imposed by a server; very large files are limited only by your device's memory.
Do I need to sign up or install anything?
Nothing to install and no account needed. Open the page in any up-to-date browser, including on a phone or tablet, and the tool is ready.
How do I save the output?
Click the Download button once the result is ready. The file is built in your browser's memory and handed straight to your downloads folder, without passing through a server.