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".
Comparing spreadsheets? Compare two lists keeps every column of a CSV, lines up matching columns when merging and fills in blank cells.
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 [email protected] and [email protected] 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.
Related free tools
What the compare email lists tool does
When you have two email lists, it's hard to tell by eye who is on both, who is missing, or how to combine them without emailing anyone twice. This tool pulls the addresses out of each list and sorts them into four results: In both, Only in A, Only in B, and Merged with duplicates removed. It's a quick way to remove unsubscribes, find new leads or join two lists safely.
Benefits
- Four answers from one clickSwitch between In both, Only in A, Only in B and Merged tabs, each with a count.
- Works with messy listsPaste plain lists, spreadsheet columns or text with names around the addresses, or open a .txt or .csv file. Addresses are picked out for you.
- Block whole domainsAdd a line like @example.com to List B and every address at that domain is treated as a match and kept out of Only in A.
- Remove unsubscribes modeOne button relabels the boxes for a mailing list and a suppression list, and jumps you to the Only in A result.
- Optional Gmail alias matchingTurn it on to treat dotted and plus-sign versions of the same Gmail address as one person.
- Useful summary lineSee how many unique addresses each list has and what share of List A is also on List B.
- Several ways to saveCopy the result, download it as .txt or .csv, or get a full report CSV that marks each address as in A, in B, both, or domain blocked.
- Pass results to the next toolSend the result straight to the List Cleaner, List Splitter, Email Separator or Email to Name tool without saving a file.
Who it is for
- Small-business owners removing unsubscribed people before sending a newsletter.
- Sales teams checking which leads in a new list are not already customers.
- Event organizers finding people who registered for two different events.
- Marketers combining two sign-up lists for one campaign without sending duplicates.
- Anyone checking a purchased or imported list against their CRM export before uploading it.
How to use it
- Paste your first list into List A, or open a .txt or .csv file.
- Paste your second list into List B. For unsubscribes, click Remove unsubscribes mode first.
- Tick the Gmail alias option if you need it, then click Compare.
- Open the tab you need and copy it, download it, or send it to another tool.
Your privacy
Both lists are compared inside your browser and are not uploaded anywhere. If you send a result to another ListaFix tool, it is held briefly in this browser tab's session storage and deleted as soon as the next tool reads it.
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 [email protected] and [email protected] 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.