Compare Two CSVs by Unique Key

Compare an old and a new version of a CSV using a key column to immediately spot added, removed, or modified rows.

Example:

How it works

Great for tracking changes in a recurring export (customer list, product catalog, inventory): import the “before” and “after” versions, specify the column that uniquely identifies a row (an ID, SKU, or email), and the tool matches rows from both files by this key to precisely list what has changed.

How are “modified” rows detected?

For each key present in both files, all common columns are compared value by value. As soon as at least one column differs, the row is classified as “modified” and the detail of each changed field (before → after) is displayed.

What happens if the columns are not exactly the same in both files?

The tool only compares columns present in both files. Columns specific to only one of the two files do not generate an error but are not taken into account when calculating differences.

100% local processing: the comparison happens entirely in your browser; your two CSV files are never sent to a server.