Compare and Merge Two Email Lists
Paste two lists to see who's on both, who's only on one, or merge them with duplicates removed. Works with messy text and CSV exports, handles hundreds of thousands of addresses, and nothing leaves your browser.
Tip: a line in List B like @example.com counts every address at that domain as a match, so it's removed from "Only in A".
What each result means
In both: addresses on both lists, for example customers who are also newsletter subscribers.
Only in A / Only in B: addresses on one list but not the other. Use "Only in A" to find who to add to list B, or to remove unsubscribes (put your unsubscribe list in B).
Merged: both lists combined with duplicates removed, in the order they first appear. Comparison ignores capital letters, so John@Site.com and john@site.com count as the same address.
How to use the Compare Email Lists
- Paste your first list into List A (or open a file).
- Paste your second list into List B.
- Turn on Gmail alias matching if your lists might contain the same Gmail user written differently.
- Press Compare, then switch between the four tabs and copy or download the result you need.
Everyday uses
Remove unsubscribes: put your mailing list in A and your unsubscribe or suppression list in B, then take "Only in A".
Find new leads: put your new lead list in A and your existing customers in B; "Only in A" shows who's genuinely new.
Combine two lists for one campaign without emailing anyone twice: use "Merged".
Check overlap between two event registrations, or between a purchased list and your CRM, before importing.
Tips for clean results
Both lists can be messy: CSV exports, pasted spreadsheets or text with names around the addresses all work, because addresses are pulled out automatically.
Run the merged list through the list cleaner afterwards to catch typos and dead domains before you send.
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Frequently asked questions
How do I remove unsubscribed people from my list?
Paste your list as List A and your unsubscribes as List B, then open the "Only in A" tab. That's your list with every unsubscribed address removed.
Does it handle capital letters and duplicates?
Yes. Addresses are compared without regard to capitals, and each address appears only once in every result.
What does the Gmail alias option do?
Gmail ignores dots and anything after a plus sign, so john.smith+news@gmail.com and johnsmith@gmail.com reach the same inbox. With the option on, they count as the same person.
Is there a size limit?
No fixed limit. Lists of several hundred thousand addresses work on a normal computer because everything runs locally in your browser.
Can I compare lists from two different spreadsheets?
Yes. Copy the email column (or the whole sheet) from each spreadsheet and paste one into each box.
Does the order of my list change?
No. Results keep the order in which addresses first appear.