Merge and Dedupe Lists
Combine two lists and remove duplicate lines.
How to use
- 1 Paste your first list into List A.
- 2 Paste your second list into List B.
- 3 Optionally enable ignore-case or alphabetical sorting.
- 4 Copy the merged, de-duplicated result.
About Merge and Dedupe Lists
The Merge and Dedupe Lists tool combines two newline-separated lists into a single clean list with every duplicate removed.
Paste one list on the left and another on the right, and the tool stitches them together, keeping the first time each value appears and dropping every repeat after that.
It is the fast way to reconcile two email lists, two sets of tags, two exports of usernames, or any pair of line-based lists where overlap is likely.
You get sensible defaults and a couple of switches.
Each line is trimmed of surrounding whitespace and blank lines are skipped, so stray spaces and empty rows never sneak through as phantom entries.
Turn on "Ignore case" to treat Apple and apple as the same item, which is what you usually want for emails and codes.
Turn on "Sort alphabetically" to put the merged result in order; leave it off to preserve the original first-seen ordering.
A running count shows how many unique lines remain and how many duplicates were stripped, so you can see at a glance how much overlap the two lists had.
Everything happens in your browser with no uploads, making it safe for private contact lists and internal data, and it keeps working offline once the page has loaded.
FAQ
Which copy of a duplicate is kept?
The first occurrence is kept, scanning List A then List B top to bottom. Later duplicates, including those within a single list, are removed.
Are blank lines and surrounding spaces handled?
Yes. Each line is trimmed before comparison and empty lines are ignored, so they never appear as separate entries in the result.