CSV Merger
Combine multiple CSV files into one in your browser — match columns by header name, add a source column and remove duplicate rows.
Drag & drop your CSV files here, or click to browse
No uploads. Your files stay on your device.
Files to merge
How it works
Drop two or more CSV files and they are stacked into a single spreadsheet-ready file right
inside your browser tab. Each file is parsed with an RFC 4180 reader, so quoted fields
containing commas, line breaks and escaped "" quotes survive, and the delimiter
(comma, semicolon, tab or pipe) is detected per file — you can mix a comma export and a
semicolon export in the same merge.
By default columns are matched by header name, so files with the same columns in a different order line up correctly and any column that only exists in some files is filled with empty values. Switch to “by column position” when your files have no meaningful headers. You can reorder or remove files, add a column recording which file each row came from, and drop duplicate rows. The merged CSV rebuilds instantly — copy it or download it. Nothing is uploaded, so customer lists, orders and exports never leave your device.
Frequently asked questions
How do I combine multiple CSV files into one?
Drag all of your .csv files onto the page at once — they are stacked into a single file straight away, with one header row at the top instead of a header repeated between each file. Reorder or remove files in the list to control the row order, then use Copy CSV or Download merged CSV to save the result. Nothing is uploaded, so the merge works even if you go offline after loading the page.
What if my CSV files have different columns or a different column order?
By default columns are matched by header name, so a file with the columns in a different order still lines up correctly, and any column that exists in only some files is added to the output and left empty for the other rows. If your files have no meaningful headers, switch "Combine columns" to "by column position" and rows are joined position by position instead. Delimiters are detected per file, so you can merge a comma export and a semicolon export together.
Are my CSV files uploaded to a server?
No. Every file is read and merged locally in your browser with JavaScript — the data is never uploaded, stored or logged, and there is no account, watermark or file-size paywall. That makes it safe for customer lists, order exports and finance data that must not leave your device.