Remove duplicate lines while keeping first or last occurrences.
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Remove duplicate lines privately in your browser.
Paste a list
Keep the first or last occurrence of each duplicate line.
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Remove repeated lines from lists, logs, or exports while keeping either the first or last occurrence.
Optional trim and case-insensitive matching help when source data is messy.
All processing runs locally in your browser. Nothing you enter is sent to a Dockzio server.
Practical guidance
This tool compares whole lines. It is useful for repeated tags, copied lists, and exact log entries, but it does not identify near-duplicates or compare a selected column in a structured file.
For three lines Apple, Banana, Apple, keeping the first occurrence returns Apple then Banana. Keeping the last returns Banana then Apple, because retained lines stay in their original relative order. The choice can therefore change the resulting order as well as which copy survives.
With case-sensitive matching, Apple and apple remain separate. With it off, they match, but the retained entry keeps its original casing. Trimming makes padded entries comparable and also removes that padding from the output. Test those options on a short sample before processing a larger list.
JS and JavaScript remain different, as do entries with different internal spacing. The tool does not merge synonyms or parse CSV quoting, spreadsheet columns, or records spanning multiple lines. Do not use it to deduplicate customers by one field when the remaining fields must be preserved or reconciled.
Keep the original, compare the retained entries, and inspect any case-sensitive codes. Blank-line removal is separate from duplicate removal, so the duplicate count need not equal every line removed from the input. Sort only after deciding whether original order matters to the destination.
Quick answers to common questions.
Learning Center
Short explainers that pair well with this tool — concepts first, then practice.