Compare Two Email Lists — Find Duplicates & Missing Subscribers
Paste two email lists and instantly see which addresses overlap, which are only in one list, and which are completely missing. Free, private, no upload required.
Live preview · Open the full tool to export results as CSV and save your comparison history.
How to Compare Two Email Lists
Email marketers, CRM managers, and operations teams compare email lists constantly — to suppress unsubscribes, find customers who aren't yet subscribers, or merge two databases. Here's how to do it in seconds:
- Export your first email listDownload it from your ESP (Mailchimp, Klaviyo, HubSpot, etc.) as a CSV. Open the file and copy just the email address column.
- Paste into List AClick in the List A box and paste. One email per line — the tool handles any spacing or blank lines automatically.
- Paste your second list into List BThis could be an unsubscribe list, a purchase list, a CRM export, or any other email collection.
- Read the three result columns"Only in A" = subscribers not in your second list. "Only in B" = addresses only in the second list. "Common" = appears in both.
- Export and use the resultsDownload the results as CSV to import back into your ESP for segmentation, suppression, or targeting.
Common Email List Comparison Tasks
- Suppress unsubscribesCompare your active list (A) against your unsubscribe list (B). The "common" section = contacts to remove from campaigns.
- Find non-subscribers who boughtCompare buyer emails (A) against newsletter subscribers (B). "Only in A" = buyers you haven't nurtured yet.
- Merge two CRM exportsIdentify which contacts exist in both systems and which are missing from one. Clean data before importing.
- Cross-check event attendeesCompare attendee lists against your subscriber base to see who you haven't captured yet.
- Audit lead generationCompare new leads from two different campaigns to find overlap and calculate unique reach.
- Deduplicate before sendingUse the "Common" section to identify duplicates across two lists before merging them for a campaign.
Frequently Asked Questions
How do I compare two email lists?
Export each email list as CSV or plain text, copy the email address column, and paste into List A and List B above. The tool immediately shows which emails are only in one list and which appear in both.
How do I find duplicate emails across two lists?
The "Common to both" column shows every email address that appears in both lists — those are your duplicates across the two lists. You can export them as a CSV file.
Can I compare an unsubscribe list against my active subscribers?
Yes. Paste your active subscribers into List A and your unsubscribes into List B. The "Common" section shows who needs to be suppressed. The "Only in A" section shows clean, active subscribers.
Does the comparison handle uppercase and lowercase differences?
Yes — by default the comparison is case-insensitive, so "User@Example.COM" matches "user@example.com". Toggle case-sensitive mode in the full tool if needed.
Is my email data safe and private?
All comparison processing runs in your browser — no email addresses are sent to any server. Safe for GDPR-sensitive and confidential contact lists.