Merge CSV files

Combines several CSV or Excel files into one, lining up columns that have different names.

Drop two or more CSV or Excel files at once, or add them one by one

Runs in your browser. The file never leaves your device.CSV or Excel, up to 200,000 rows per file

Remove duplicates from CSV

Then

Split CSV

Email me this report

A short summary of this run: the counts and settings, never your rows. Your file stays in your browser.

The counts from this runThe settings you usedNo file, no rows, no saved link

Ken cleans every list you import, then verifies it.

Import once. Ken dedupes, formats and verifies every address, and keeps the flags with each lead.

Start free - 1,000 credits, no card

What merge CSV does

It appends two or more CSV or Excel files into one. Columns are matched by name across files, so "First Name", "first_name" and "FirstName" land in the same column, and you can fix any match by hand. Columns that only exist in one file are kept, with empty cells for rows from the other files.

The files are read in your browser and never uploaded.

How to read the result

The mapping table shows each output column and the column it came from in every file. Rows per file and total rows are counted above the preview. A column that matched in only some files is marked so you can check it was not a near miss, such as "Company" in one file and "Organization" in another.

How to use it

Drop all the files at once. Check the mapping, point each output column at the right column in every file, and download. If you merge exports from different sources, run remove duplicates on the result, because the same person often appears in both. Leave the Source File column on if you need to know which file a row came from.

Why it matters for cold email

Campaign lists usually come from several exports: a Sales Navigator pull, an Apollo search, a conference list. Pasting them together by hand misaligns columns, and a misaligned column puts a job title where the first name should be. That shows up as "Hi VP of Sales," in someone's inbox.

Questions

How do I merge multiple CSV files into one?

Drop them all here. Columns with the same meaning are matched by name, you confirm the mapping, and you download one file. No command line or formulas needed, and the files stay on your device.

What if the files have different columns?

The output has every column from every file. Rows from a file that did not have a column get an empty cell there. You can drop columns you do not need before downloading.

Can I merge CSV and Excel files together?

Yes. Excel files are read from the first sheet, and the output can be CSV or Excel.

Does merging remove duplicates?

Not by default: merge appends every row. Switch on "Remove duplicate emails after merging" to drop people who appear in more than one file, or run the result through remove duplicates.

How do I merge CSV files on the command line?

On macOS or Linux, cat a.csv b.csv > all.csv joins the files, but it repeats the header row and does not match columns. That only works when every file has exactly the same columns in the same order.