List Union Dedupe
Combine lists and remove duplicates.
Merge and dedupe lists
This joins one or more lists and removes duplicates, keeping the first occurrence — the fast way to build a clean master list from several overlapping sources.
It is how you build one clean master list from several overlapping sources — combined mailing lists, merged tag sets — keeping each entry once in its first-seen order.
Exact matches only
Items differing by case or spacing count as distinct, so normalise first if needed. The dedupe runs in your browser. Your lists are merged on your device and never uploaded.
Frequently asked questions
What does this list union dedupe do?
Combine several lists into a clean unique union.
Which version of a duplicate is kept?
The first one, in its original capitalization. Later repeats are dropped, so the output order follows first appearance.
How do I combine several lists?
Paste them one after another, one item per line. Blank lines are ignored, so you can leave gaps between lists.
What does case-insensitive matching do?
It treats "Email" and "email" as duplicates. Leave it off when capitalization matters, such as case-sensitive codes or IDs.
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