How do I get a unique list without duplicates?

Turn on Dedupe items before you compare, or after you review Dupes in A, keep only one copy of each value when you export. For merging two sources into one unique set, use the Union tab instead.

Find duplicate lines before you trust the counts

Last updated: 2026-08-26

Exports often hide repeats: the same email twice, the same SKU pasted from two sheets, or blank-looking lines that only differ by a trailing space. ListDiff surfaces those in the Dupes in A / Dupes in B tabs after you compare.

Single-list check

Paste everything into List A.
You can leave List B empty if you only care about repeats inside A.
Leave trim on so sku-1 and sku-1 can match.
Click Compare lists → open Dupes in A.

Dedupe vs Dupes tab

Dupes tab — shows which values repeat so you can inspect data quality.
Dedupe option — collapses repeated keys before set comparison so A only / Intersection treat each key once.

For combining two sources into one unique file, use merge two lists (Union).

Example

List A: apple, banana, apple, cherry
Dupes in A: apple (appears more than once)

Paste a list to check duplicates

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FAQ

How do I find duplicates in a list online?

Paste into List A, compare, open Dupes in A.

How do I export a unique list?

Use Dedupe before compare when you want set keys, or merge with Union when combining two lists. Then download CSV.