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Free Online Remove Duplicate Lines

Keep the first occurrence of each exact line.

Your input stays on this device. Processing is bounded; regex runs in a worker with a two-second timeout.

Result



How to use Remove Duplicate Lines
Keep the first occurrence of each exact line. Matching is case-sensitive and exact. Whitespace differences remain distinct, and the first occurrence is retained.
  1. Set Input.
  2. Run the tool, review the result and its stated limitations, then copy or download if needed.
Example & practical use
Keep the first occurrence of each exact line. The example below demonstrates Input.
Example input:
{
  "text": "a\nb\na"
}
Expected result (relevant fields):
"a\nb"
Features & result limitations
Matching is case-sensitive and exact. Whitespace differences remain distinct, and the first occurrence is retained.
Frequently asked questions
What inputs does Remove Duplicate Lines accept?
Input
How should I interpret the Remove Duplicate Lines result?
Matching is case-sensitive and exact. Whitespace differences remain distinct, and the first occurrence is retained.
Where does Remove Duplicate Lines process my data?
Inputs are processed locally in your browser. Submitted text is not sent to external services. A successful-run event increments an aggregate tool counter without your input.