About the Merge CSV Files
Data often arrives in pieces: one file per month, per region or per store. This tool puts them back together. Drop several CSV or TSV files, and it combines them into one file. By default it matches columns by their title, so files with the same columns in a different order, or with extra columns, still line up; missing cells are left empty and you are told about them. If all your files have the same layout, you can stack the rows by position instead. Options let you add a column with the name of the source file, remove rows that appear twice and choose the separator for the result. Everything is processed in your browser, so confidential data does not leave your computer.
Updated October 2026
How to use the Merge CSV Files
- 1Add your CSV or TSV files.
- 2Choose to match columns by name, or stack by position.
- 3Tick Add a column with the file name if you want to know where each row came from.
- 4Tick Remove rows that appear twice if needed.
- 5Check the preview and download the merged file.
Choosing the matching mode
Matching by name is the safest choice for files from different sources, because a column called Email stays in the Email column even if it sits in a different position. The comparison ignores capital letters and spaces around the title, so Email and email are the same column.
Stacking by position is simple and fast for files that came from one export and share a layout. If the titles differ, the tool warns you, so you can switch to name matching.
Checks to make after merging
- Count the rows: it should equal the sum of the files minus the headers.
- Look at empty cells in columns that exist in only some files.
- Make sure dates and numbers look the same in all rows.
- Check for repeated header rows copied from other files.
- Sort the result by a key column to spot errors.
Related tools
Look at the result in the CSV Viewer, divide a large file again with the CSV Splitter, or switch the separator with the CSV Delimiter Changer. Convert the final data with CSV to JSON Converter or open it as a spreadsheet using CSV to Excel. Keep the original files in case you need to repeat the merge.
Features
- Match by column name or stack by position
- Different column order handled
- Source file column
- Duplicate row removal
- Comma, semicolon or tab output
- Warnings about missing columns
- Private, runs in your browser
Frequently asked questions
How do I merge CSV files with different columns?
Use Match by column name. The result has all the columns that appear in any file. Cells for columns missing in a file are left empty.
Do all files need a header row?
Yes. The first row of each file is read as the column titles. Without a header the first data row would be treated as titles.
What separators are supported?
Commas, semicolons, tabs and pipes in the input files are detected automatically for each file. You choose the separator for the output.
What happens to special characters?
The output is UTF-8 with a byte order mark so that Excel shows accents correctly. Fields with commas, quotes or line breaks are quoted properly.
How are duplicate rows detected?
Two rows are the same when every cell is the same. The source file column is ignored for this check.
Is there a size limit?
No fixed limit, but very large files can be slow because they are held in the browser's memory. For files over a few hundred megabytes use a script or a database.
Are my files uploaded?
No.