Merge CSV Files Online – Combine Multiple CSV Files into One
How to merge multiple CSV files into one online
- Click the upload area or drag and drop two or more CSV files into it.
- Choose whether each CSV has a header row and pick a merge mode: simple append or align by column name.
- Optionally turn on duplicate row removal if you want to deduplicate the merged result.
- Click the merge button and then download the merged CSV file.
Privacy
CSV merging happens completely in your browser. Your CSV files are not uploaded to any server and no data is stored after you close the page.
CSV Merge FAQ
Can I merge CSV files with different columns?
Yes. Use the merge mode that aligns by column name. The tool builds a unified set of column names from all files. Missing values in some files are left empty in the merged result.
Do all CSV files need to have a header row?
It is recommended that every CSV has the same header row so the merged result is easy to understand. If you disable the header option, the tool generates numbered column names and merges by position.
Is there a file size limit when merging CSV files?
The tool runs inside your browser, so the practical limit depends on your device memory and CPU. It can handle reasonably large CSV files, but extremely large datasets may be slow or fail to load.
Are my CSV files uploaded or stored anywhere?
No. All parsing and merging are done locally in your browser. The files never leave your device.