Compare two CSV files row-by-row using a chosen key column. See which rows were added, removed, or changed — with cell-level highlighting of every value that moved.
Rows are matched by the value in the chosen key column. If the key column is left blank the first column of the header is used. Row matches that share a key but differ in any other cell are flagged as changed; cells that diverge are highlighted in-place. Rows present only on one side are flagged added or removed. Headers from the new file are used as the canonical column order; columns added or dropped between files appear with — on the missing side.