Merge CSV files into one

Steps

1. Open Rowlode and choose all the files at once (or add more later with Add more files).
2. Columns with the same header name (ignoring case) are combined; columns that exist only in some files are added and left empty elsewhere.
3. Tick Add a source_file column to see which file each row came from.
4. Optionally remove duplicates across the files, then export one CSV or Excel file.

Files without a header row

If the files have no header, set First row to is data; columns are then matched by position (Column 1, Column 2, …).

Into one Excel workbook

Choose Excel (.xlsx). If the combined result has more than 1,048,575 rows, choose more sheets in one workbook to keep everything in one file, with the rows continued on the next sheet.