CSV Lens is a free browser utility for the cleanup step between a data export and its next import. I am sharing my own project, developed with AI assistance.

Choose whether duplicates mean complete rows or matching values in specific columns. Matching the email column keeps the first record for that address; it does not merge the other fields. Preview the retained rows and download a cleaned CSV or TSV.

Files and pasted table content are processed locally in the browser. The site separately collects limited usage events and optional feedback. It supports UTF-8 files up to 5 MiB, quoted commas and multiline fields, and formula-protected export. It does not handle XLSX, fuzzy matching or record merging.

The site includes worked examples, a method guide and explicit limits. It has been checked with formula/parser tests and real browser downloads; user demand and revenue have not yet been validated.

If you try it, a small non-sensitive example of an unexpected result would help improve the tool.