How to combine CSV files

Stacking is where we take two (or more) CSV files and combine the columns, one on top of the other (vertically). For example to turn:

Merge CSV files


Merge CSV file


Merged CSV file

(You can also join CSV files side-by-side using a common ‘key’ column)

The above is easy to do in Easy Data Transform, even if the columns in the two CSV files are different:

  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 file.
  2. Drag the input items into the vertical the order you want to stack them (the top one at the top).
  3. Select the two (or more) input items you wish to stack using Ctrl+click (PC)/Cmd+click (Mac) (or by dragging a box around them).
  4. Click the Stack button in the Left pane. A blue transform item is added.

Combine CSV files

The CSV files are now stacked in the vertical order shown on screen. Swap the vertical order of the input items in the Center pane, by dragging and dropping, to change the stacking order.

If you want to stack column N of the first table above column N of the second table (regardless of column name), set Align columns by to Column number.

If you want to stack columns by common column header names (even if the columns aren’t in the same order), set Align columns by to Header name. Matching is sensitive to case and white space.

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

If you need to combine a large number of CSV files into one file, you can do it using the batch processing feature. Just set the output file to have Write mode of Append.

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

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