Common Emails Finder

The Common Emails Finder compares two lists of email addresses and returns only the ones that appear in both. It calculates the intersection of the two sets, so what you get back is a clean list of the contacts the lists have in common, with everything unique to just one side left out. It replaces fiddly spreadsheet lookups with a single click.

Finding shared contacts is useful in many everyday scenarios. You might check which of your newsletter subscribers are also paying customers, discover which prospects appear on two different sourced lists, or confirm which addresses on a supplied file already exist in your own records. A statistics panel reports the unique size of each input list and how many addresses they share.

Everything runs locally in your browser using JavaScript, so neither list is ever uploaded or stored. Matching is case-insensitive so capitalisation differences do not hide a genuine match, and duplicates within each list are collapsed first, so the intersection reflects distinct people. Optional lowercasing and alphabetical sorting let you tidy the output in the same step.

Features

• Returns only the addresses present in both lists, giving you the exact intersection of the two inputs.
• Extracts valid emails from each list automatically, ignoring surrounding words, punctuation, and formatting.
• Matches addresses case-insensitively so capitalisation differences never hide a genuine shared contact.
• Collapses duplicates inside each list so the shared result reflects distinct people rather than repeats.
• Offers optional lowercasing and alphabetical sorting so the overlap list comes out tidy and consistent.
• Shows a live statistics panel with unique counts for each list and the number of shared addresses.
• Runs entirely in your browser so both contact lists stay private on your own device at all times.

How to use Common Emails Finder

1. Paste your first list of email addresses into the List A input box on the left.
2. Paste the second list you want to intersect with the first into the List B input box.
3. Enable Lowercase or Sort A to Z if you want the shared addresses normalised or ordered.
4. Click the Find common emails button to compute the intersection of the two lists.
5. Read the statistics panel to see how many unique addresses each list held and how many are shared.
6. Copy the overlap list to your clipboard, or export it as a TXT or CSV file for later use.

Benefits

• Reveals exactly which contacts two lists have in common without building lookup formulas by hand.
• Helps identify subscribers who are also customers so you can target or exclude that overlapping group.
• Confirms how much two sourced or purchased lists overlap before you rely on either one for outreach.
• Reduces errors because case-insensitive matching and automatic deduplication remove common pitfalls.
• Keeps confidential lists private since all processing happens locally with nothing uploaded anywhere.
• Produces a clean, exportable overlap list that is ready to import into another tool or platform.

The intersection contains only addresses that exist in both list A and list B; anything unique to a single list is deliberately excluded. Because duplicates inside each list are collapsed first, an address that appears many times in one list still contributes just one entry to the result, so the shared count describes distinct people rather than raw rows.

Matching compares the whole address in a case-insensitive way, so entries that differ only in capitalisation are still recognised as the same contact. The tool does not normalise provider-specific aliases such as Gmail dots or plus-addressing, so alias forms of one mailbox are treated as different addresses. Run both lists through the Email Case Normalizer first if you need the loosest possible matching.

All comparison happens with JavaScript in your browser, so nothing you paste is transmitted or stored, which keeps the tool safe for sensitive customer and subscriber data. For the opposite views of the same two lists, use the Email List Difference Checker to subtract one from the other, or the Email List Comparison Tool for a complete breakdown of unique and shared addresses.