Identify and highlight duplicate rows in any CSV by key column. Download a marked CSV showing which rows are duplicates. Browser-based, no upload.
Privacy: Everything runs locally in your browser. Your source file is not uploaded to JAD Apps servers.
Mark duplicate rows in a CSV without deleting them. Adds an `_is_duplicate` column with `YES`/`NO` so you can review which rows are duplicates before deciding to delete. Use CSV Deduplicator to actually remove them.
Free is enough for most one-off jobs. Pro raises the file and batch caps; Pro + Media unlocks GB-scale streaming and unlimited duration.
Larger files supported on Developer (5 GB CSV) and Enterprise (unlimited). All processing happens in your browser — files never reach a server.
Drop your CSV
Headers populate the column dropdown.
Pick the column to check
Email, SKU, ID, or any column where duplicate values are notable. Toggle case-sensitivity if needed.
Click Find duplicates
The tool counts duplicate groups, total extra copies, and unique values. Each row is tagged YES or NO.
Download the marked CSV
Filename gets a `.duplicates-marked.csv` suffix. Sort or filter on the `_is_duplicate` column in Excel/Sheets.
Sometimes duplicates are real (legitimately repeated transactions) and sometimes they're errors. Marking lets you review before committing.
All rows that share the same value in the chosen column. A group of size 3 means three rows with the same value, so 2 are 'extra copies' (the first is kept as the canonical).
Empty values are grouped together — if 50 rows have empty emails, they all count as duplicates of each other.
Privacy
Everything runs locally in your browser. Your source file is not uploaded to JAD Apps servers.
Remove duplicate CSV rows by choosing a unique key column like Email, SKU, phone, or ID. Browser-based, no upload.
Run a CSV sanity check in your browser. Find row-width drift, type mismatches, duplicate headers, encoding issues, and empty cells.
Clean a CSV file online — remove empty rows, trim whitespace, deduplicate, and repair malformed rows. Free, browser-based, no upload.