What this does

Find and remove duplicate rows from a CSV. You choose what counts as "the same row":

• All columns — drop only exact duplicates
• One or more columns — keep just one row per email, per customer ID, per SKU, etc.

For each duplicate group, you can keep the first occurrence or the last — useful when later rows have updated info.

Bonus features

• Trim whitespace before comparing — so "alice@x.com " matches "alice@x.com"
• Case-insensitive match — so Alice@X.com matches alice@x.com
• Preview the duplicates before downloading — see exactly what gets dropped