To merge spreadsheets from MS Excel, Libre Office Calc, Google Sheets, etc., you must first save the sheet as a CSV (comma-separated values) file. In Excel and programs like it, click "Save As" and save as a ".csv" file. In Google Sheets, click "File > Download > Comma-separated values (.csv, current sheet).
Once you have the CSV files, click "Choose File" to upload them. Click the checkbox next to the files you want to merge and then click the "Start Merge" button.
Selected Files:
First, choose the files that you want to merge together. Once that is done, you can select the columns
that you want in your new file.
The following example illustrates choosing column f1-A from
file 1 and f2-B from file 2.
The order of the new file is the same as the starting files.
Rows are matched using the row number.
Using key columns f1-A from
file 1 and f2-A from file 2 (the
key column does not have to be one of the columns in the merged file). Rows are combined only where the
key columns are the same in each row of each file. Multiple key columns can be used.
The rows of the new file are built starting with
file 1 followed by file 2. If the file contains the chosen
column, the data is put into the row; if the file does not contain the chosen column, an empty space is put
into the column.