Email list overlap checker: compare 3 or more lists at once
In short: Compare up to six lists or CSVs: an overlap count for every pair, addresses on every list or on only one, and a merged deduplicated download with which lists each address came from. Limit: It matches addresses; it doesn't match the same person under two different addresses.
An email list overlap checker compares several lists at once. Paste or upload up to six, such as webinar attendees, newsletter subscribers and trial signups, and you get how many addresses every pair shares, who is on all of them, who is on only one, and one merged list with each address once and the lists it appeared on. Matching ignores case, and optionally Gmail dots and +tags.
Price: this tool is free. Checking a whole email list is from $9/mo, and the first 100 checks are free with Google, no card. See pricing
Runs in your browser; nothing is uploaded.
Sample result
12 rows across 3 lists are 7 people; 4 are on more than one list.
- Lists
- 3 lists, 7 unique
- On every list
- 1
What this means for you
Merge before you send, or those people get the same email more than once.
- Overlap for every pair
- On all lists or only one
- Merged, deduplicated download
- Gmail dots and +tags matched
- Compare
- Dedupe
- Merge
By SimpleVerifier Team · Last updated · Runs in your browser; nothing you paste is sent to us
How do I compare more than two email lists?
- Paste each list into its own box or upload a CSV or TXT file per list, and name the lists. Add boxes up to six.
- Leave "Treat Gmail dots and +tags as the same inbox" on unless you need exact spellings.
- Press Compare the lists to see the pair-by-pair table and the totals.
- Download the merged deduplicated list, the addresses on two or more lists, or the ones on every list.
Example
- You enter
- Three lists of four addresses each: Webinar, Newsletter and Trial signups, sharing
[email protected]and with[email protected]and[email protected]on two of them. - You get
- 12 rows come down to 7 unique addresses. 4 are on two or more lists and 1, jane's, is on all three. The pair table shows Webinar and Trial signups share 2. With the Gmail option on, the two johnson spellings count as one inbox. Download the merged list with a lists column.
- Limits
- Up to six lists, each up to 25 MB. Runs in your browser.
How do I find duplicates across several email lists?
Put every list in, and read the table: each cell is the number of addresses two lists share, and the diagonal is each list's own unique count. The totals above it show how many unique people the lists hold together and how many appear on more than one. That answers questions a two-list comparison can't: whether three lead sources are selling you the same people, how much of a webinar audience already gets the newsletter, or how many people a send to every segment would reach twice.
For the two-list jobs, A minus B, such as removing unsubscribes from a send list, compare two email lists is built for that. To stack several exports into one file with all their columns, use CSV merge.
Why does overlap matter before a send?
Every address on two lists is a person who gets the same campaign twice if each list is sent separately, which drives unsubscribes and spam complaints, and Gmail asks bulk senders to keep reported spam under 0.3% (Gmail sender guidelines). It also costs money twice: most email platforms bill per contact, and most verifiers per address checked. Merge first, verify the merged list once, then send.
Matching ignores capital letters and stray wrapping. With the Gmail option on, [email protected] and [email protected] count as one inbox, as Gmail treats them.
Who uses this tool, and for what?
- Marketers
- See how much of a webinar audience already subscribes to the newsletter before deciding whether to send both.
- Cold emailers
- Check how many leads three data vendors share before paying for all three lists.
- Event teams
- Find who registered for every event in a series, and who came only once.
What can’t this tool tell you?
- It matches addresses; it doesn't match the same person under two different addresses.
- The merged download keeps the address and list names, not every column.
- It doesn't check which merged addresses still work.
Common questions
- How many lists can I compare?
- Up to six at once, each pasted or uploaded as a CSV or TXT file of up to 25 MB.
- Does it keep my other columns?
- The merged download has the address, how many lists it's on and their names. To keep every column, merge the files with CSV merge.
- Is a duplicate within one list counted twice?
- No. Each list is deduplicated first, so the counts are unique addresses.
- How do I find addresses that are only on one list?
- The second table shows, for each list, how many of its addresses appear on no other list.
- Is anything uploaded?
- No. The comparison runs in your browser.
Sources
A tidy list can still be full of dead addresses.
Extracting, deduplicating and syntax checks all work on the text of an address. None of them can tell whether the mailbox exists. Only the server that hosts it can answer that, through an SMTP check, and that is what the paid product does.
- Upload the cleaned file as it is: CSVs up to 100,000 rows
- A real SMTP mailbox check on every row, with catch-all detection
- Small list? Starter at $9/mo covers 2,500 emails a month, cancel anytime
Plans from $9 a month, cancel anytime, no contract. Sign in with Google and your first 100 email checks are free, no card. The free tools stay free either way.