Use this calculator to remove duplicates from a list and keep each value once. Paste items into Input List and read the deduplicated result in Output. First-seen order is preserved.
Use commas, spaces, or new lines to separate items. The first occurrence of each value is kept.
A list can contain the same value more than once. Turning a list into its unique (deduplicated) form keeps each value only once — similar to converting a multiset into a set, while optionally preserving the order of first appearance.
Suppose a shopping list accidentally repeats some items:
After deduplication (first-seen order), you get:
Each value appears once; later repeats are dropped.
Try it!This tool keeps the first time each item appears. Later duplicates are removed without re-sorting the list.
Values are compared exactly as typed. Apple and apple count as different items.
In set theory, sets do not contain duplicates. Use this tool when your data starts as a messy list and you need a clean unique collection.
Paste a list with repeats. The tool keeps the first occurrence of each value and drops later duplicates. Comparison is exact and case-sensitive. Ideal before running set union or intersection on cleaned lists.