How to join CSV files

Joining is where we take data from two CSV files and merge the rows, side-by-side (horizontally), using a common (‘key’) column. For example to turn:

Join CSV files


Joined CSV files

(You can also combine CSV files one on-top of another)

This is very easy in Easy Data Transform:

  1. Install Easy Data Transform on your PC or Mac, if you haven’t done so already. It will only take a minute. There is a fully functional free trial and you don’t have to give us your email or sign up to anything.
  2. Start Easy Data Transform. Make sure the Auto Run button is pressed in.

Auto run on

  1. Drag the CSV files you want to merge onto Easy Data Transform. A pink input item will be added for each sheet with data.
  2. Drag the input items into the order you want to stack them (one you want on the left, at the top).
  3. Select the two input items you wish to join using Ctrl+click (PC)/Cmd+click (Mac) (or by dragging a box around them).
  4. Click the Join button in the Left pane. A blue transform item is added and selected.
  5. In the Right pane set the Top key column and Bottom key column to the common (‘key’) column (Easy Data transform may have already guessed them correctly).

Join two CSV files

The CSV files are now joined with the top input item on the left of the table. Easy!


When you are happy with the results output the result into a new CSV file or Excel spreadsheet.

Join is just one of the 66 transforms that Easy Data Transform supports.

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