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ListDiff

Compare email lists before you send

Last updated: 2026-08-26

Marketing and ops teams often need the same job: take a send list, subtract people who already unsubscribed (or sit on a do-not-contact file), and keep the rest. ListDiff does that as a plain two-list compare in your browser—no CRM login, no upload of contacts for the compare step.

Which result tab answers which job?

  • A only — emails in the send list that are not on the suppression list. This is the usual “safe to keep” set after cleanup.
  • Intersection — addresses present in both lists (overlap / already suppressed).
  • Union — one merged unique list when you are combining two sources.
  • Duplicates — repeats inside A or B that can inflate counts before you export.

Suggested settings for email

  • One address per line (or export a single email column from a CSV).
  • Leave Trim and Ignore empty on.
  • Leave Case off unless you know your export is strictly cased.
  • Strip a header row like email before you compare if it is not a real address.

Example

List A (send): a@brand.com, b@brand.com, c@brand.com
List B (unsub): b@brand.com, d@brand.com
A only: a@brand.com, c@brand.com — use this after suppression cleanup.

Paste email lists here

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Privacy

Comparison stays on your device. See Is ListDiff safe? and Privacy. You remain responsible for consent and local email laws—this page only helps you compare files you already have.

FAQ

How do I remove unsubscribes from an email list?

Send list in A, unsubscribe or exclusion list in B, then copy A only.

Does ListDiff upload my email lists?

No. The compare step runs in the browser. Addresses are not sent to a ListDiff server for processing.

Should comparison be case sensitive?

Usually no. Leave case off so Name@Brand.com and name@brand.com match.

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