Click to upload or drop several CSV files
Two or more CSV, TSV or TXT files (Excel files work too) — merged in order, nothing uploadedAbout merging CSV files
Monthly exports, one CSV per shop, one file per day of logs, sign-up lists from several forms — data often comes in many small CSV files that you need as one. Copying and pasting them in Excel takes time, and the header row ends up in the middle of your data again and again.
This tool merges your CSV files into one file with one header row. It reads each file's delimiter by itself, lines up the columns by their names, and keeps every value exactly as it was typed. Save the result as one CSV or as an Excel workbook.
Everything runs in your browser. Your files are never uploaded.
Features
- Many files at once — pick or drop them together; the list is the order
- One header row — the column names are written once, at the top
- Columns matched by name — files with columns in another order still line up
- New columns kept — a column that only some files have is added, with empty cells elsewhere
- Any delimiter — comma, semicolon, tab or pipe, found per file
- Values as typed — leading zeros, long IDs and dates are not changed
- Source file column — optional, so you know where each row came from
- CSV or Excel out — one CSV (your delimiter) or one .xlsx sheet
One header, columns matched by name
Say you have two exports. The second has the columns in another order, and a phone column instead of a city:
contacts-may.csv
| name | city | |
|---|---|---|
| Ada | ada@example.com | London |
contacts-june.csv
| name | phone | |
|---|---|---|
| jose@example.com | José | +34 600 000 000 |
With Match columns by their header name on (the default), the merged file is:
| name | city | phone | |
|---|---|---|---|
| Ada | ada@example.com | London | |
| José | jose@example.com | +34 600 000 000 |
The first file sets the column order; new columns go at the end. Names are matched without caring about upper or lower case or spaces at the ends. The line under the list tells you how many columns were not in every file.
Turn matching off to simply stack the rows as they are — column 1 under column 1 — which is right when the files have no header row, or when you know the columns are the same.
Delimiters, quotes and accents
- Each file's delimiter is found by itself, so a comma file and a semicolon file can be merged together.
- The merged CSV uses the first file's delimiter, or the one you pick.
- Values with commas, quotes or line breaks inside are quoted correctly in the result.
- Files are read as UTF-8, UTF-16 or older Windows text, so names like José or Zürich stay right. If one of your files starts with a BOM (the mark Excel likes), the merged CSV gets one too.
- Empty lines are left out.
CSV or Excel?
- One CSV file — every value exactly as in your files. Best for importing into another program.
- Excel workbook (.xlsx) — one sheet named "Merged". Plain numbers (like 149.90) become real numbers you can add up; values with a leading zero (02134) stay text.
Frequently asked questions
How do I merge CSV files into one?
Select all the CSV files in the file picker (or drop them on the box together). Check the order, then click Download merged file.
Will the header row be repeated?
No. With "Keep one header row" ticked, the column names are written once at the top. The first row of every other file is treated as its header and not copied as data.
Can I merge CSV files with different columns?
Yes. Keep "Match columns by their header name" on. Every column from every file appears once, and rows from files without that column get an empty cell.
Does it change my numbers or dates?
Not in the CSV result — every value stays exactly as typed. In the Excel result, plain numbers become numbers; leading zeros and dates stay as you typed them.
How many files can I merge?
As many as your browser can hold in memory — usually hundreds of files or millions of rows. Nothing is uploaded, so there is no upload limit.
Is my data safe?
Yes. The files are read and merged inside your browser. Nothing is sent to a server.
Related tools
- Merge Excel Files — combine XLSX files, or one tab per file
- Merge Text Files — join a whole folder of CSV or TXT files
- Remove Duplicate Rows — clean the merged list
- CSV to Excel — one CSV to a real workbook
- Split Excel File — the other way: one big file into parts
How to use it
- Click Click to upload, or drag two or more CSV files onto the box
- Use the arrows to put the files in the right order
- Keep Keep one header row and Match columns by their header name ticked (untick them for files with no header)
- Tick Add a column with the source file name if you want to see where each row came from
- Choose Save as: one CSV file (and its delimiter) or an Excel workbook
- Check the preview, then click Download merged file
