Merge CSV Files Online

Merge multiple CSV files into one XLSX worksheet. Learn how headers, UTF-8 text, duplicate rows, and different columns are handled.

How to use this tool

1. Select the supported file or files.
2. Review the available options.
3. Run the tool and download the result.
4. Open the output and verify important data.

What this tool does

Append records from multiple CSV files into one XLSX worksheet.

Important output limits

Different header names create separate columns. Standard comma-separated UTF-8 files are the most reliable input.

Frequently asked questions

Are files uploaded to an application server?

Spreadsheet contents are processed in the current browser tab.

What should I check after download?

Different header names create separate columns. Standard comma-separated UTF-8 files are the most reliable input.

Can I use this on a phone?

The interface works in modern mobile browsers, but large files may exceed device memory.

Should I keep the original file?

Yes. Keep a backup and verify generated output before relying on it.