FREE TOOL · 100% CLIENT-SIDE · NO UPLOAD

CSV duplicate risk checker.

Drop a CRM export and see the duplicate risk before you merge anything: exact duplicates, case variants, email-alias variants, empty keys, and formula-injection traps. The file never leaves your device — this page has no upload, no analytics on your data, no server.

Drop your .csv here or click to choose a file · runs locally in your browser
Try it on a demo file (no file of your own needed)
name,email,phone,company
Jon Smith,[email protected],+1 415 555 0138,Acme
Jane Doe,[email protected],+1 415 555 0139,Acme
Jon Smith,[email protected],+1 415 555 0138,Acme
=2+5+cmd|' /C calc'!A0,[email protected],,Acme Co
Sara Lopez,[email protected],+1 628 555 0142,Bluebird
Sara  Lopez,[email protected],,Bluebird

PRIVACY: parsing happens in your browser with plain JavaScript. No fetch, no beacon, no storage. Close the tab and it's gone.
LIMITS: this checker shows RISK, not truth. It never merges anything — that's the point.

Related

After the diagnosis.

Cleanup

Full cleanup pass

Logged, reversible dedupe with flagged exceptions — $300–800 per ≤10k batch.

Migration

Importing soon?

Pre-migration pack — mapping, issue log, staging.

Method

How we work

Sandbox-only, NDA, ±0 reconciliation — the whole method in writing.