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ListDiff

Merge two lists without duplicates

Paste two sources. Get one unique list—List A order stays, then new items from B are appended. The merge stays in your browser.

Free Local processing No signup Unique merge

Tool

List A (kept first)
0 lines
List B (new items appended)
0 lines
Updates as you type

Paste two lists—the unique merge updates automatically.

Need missing vs extra items instead? Use list compare. Cleaning repeats inside one list? Use find duplicates.
Compare lists Find duplicates Three lists Which tool? Guide

How it works

  1. Paste source one into A and source two into B—or try Example.
  2. Leave Trim and Ignore case on for emails and mixed-case exports.
  3. Read the merged unique list (A first, then new from B).
  4. Copy the merged list or the stats line for a ticket.

Good for

  • Yesterday’s customers plus today’s signups.
  • Two regional SKU or tag files into one catalog seed.
  • Combining two invite lists before a send.
  • Private pastes—no account for the merge step.

Quick answers

Merge vs compare? Merge = one unique list. Compare = missing / extra / overlap.

Repeats inside one file first? Use find duplicates, then merge.

Three sources? Prefer three-list compare, or merge twice.

FAQ

How do I merge two lists without duplicates?

Paste A and B above, then copy the merged unique list. Overlaps keep A’s spelling.

Is merge the same as list compare?

No. See also the merge guide if you use the Union tab on the main list tool.

Does my list leave the browser?

No for the merge step. See Is ListDiff safe?.