Merge CSV files with different columns

Step-by-step approach

1. Make sure both files have descriptive header rows and use a consistent delimiter.
2. Open CSV File Merger and select both source files.
3. The merger builds a union of header names; columns missing in either file are blank.
4. Check for slightly different names such as Customer ID versus CustomerID before merging.
5. Verify the result and download a separate combined file.

What this does not solve

Browser tools can validate known structures and transform available data, but cannot restore deleted or corrupted bytes, infer unknown business facts, or guarantee that a target system will import every field as intended.