Free tools // Deduplicator
Data Deduplicator
Find and remove duplicate rows in a CSV. Compare on every column, or only the ones that matter — email, ID, name — then export the clean set. Everything runs in your browser; the file never uploads.
Client-sideNo signupCSV up to 5 MB
Deduplicate a file
CSV · max 5 MBCompare columns
Select which columns to use for duplicate detection. Rows matching on all selected columns count as duplicates.
Duplicate rows — first 20
Every fact in your file, exactly once.
How it works
Trimmed · Case-insensitiveDuplicate records skew counts, double-send emails, and quietly compound — bad data costs a typical company 15–25% of revenue (Thomas C. Redman, MIT Sloan Management Review). This tool catches the exact and near-exact copies before they do damage.
Choose the match columns
Two rows are duplicates when they agree on every column you select. Match on email alone to catch re-entered contacts; leave every column checked to catch exact copies. Values are trimmed and compared case-insensitively, so Jon@acme.com matches jon@acme.com.
Preview before you commit
The first 20 duplicate rows are shown before anything is removed, along with total, unique, and duplicate-rate counts. Nothing changes until you download — the first occurrence of each row is kept, later copies are dropped.
Private by design
Parsing and comparison happen entirely in your browser. The file is never uploaded, logged, or stored — close the tab and it's gone. Export the deduplicated set, the duplicates on their own, or both.
Questions
Straight answersHow are duplicates detected?
Each row is reduced to a key built from your selected columns — values trimmed of whitespace and lowercased. Rows that produce the same key are duplicates. It's exact matching on the columns you pick, not fuzzy matching.
Which copy of a duplicate is kept?
The first occurrence in file order stays in the deduplicated export. Every later copy goes to the duplicates export. If a specific copy should win, sort the file so it comes first.
Does my file get uploaded anywhere?
No. The tool runs on your machine using PapaParse in the browser. Your data never touches our servers — which is also why there's no file-recovery if you close the tab.
What are the limits?
CSV or TXT files up to 5 MB, five runs per hour. Need bigger files, fuzzy matching ("Jon Smith" vs "John Smith"), or dedup across systems? That's a service job — the audit is free.