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What Does This Tool Do?

Remove Duplicate Lines scans your text line by line and keeps only the first occurrence of each unique line. The original order is preserved - only the duplicates are removed. This is useful for cleaning up lists, deduplicating data exports, and processing log files.

Available Options

Common Use Cases

How It Works

The tool splits your input by newline characters, processes each line according to your selected options, and builds a set of seen values. Each line is kept only on its first occurrence. The result maintains the order of first appearance - it does not sort the lines.

Frequently Asked Questions

Does this sort the lines?

No. The tool preserves the original order of lines, removing only duplicates. The first occurrence of each line is kept, and subsequent duplicates are dropped.

What counts as a duplicate?

By default, lines must match exactly including case and whitespace. Use the options to make comparison case-insensitive or to ignore leading/trailing whitespace.

Is there a line limit?

No hard limit. The tool handles tens of thousands of lines easily since all processing happens locally in your browser. Very large files may take a moment to process.

Frequently Asked Questions

Does it preserve the original order?

Yes — the first occurrence of each line is kept, and order of the remaining lines is unchanged.

Can it ignore case when deduplicating?

Yes. A case-insensitive option treats "Hello" and "hello" as duplicates.

How many lines can it handle?

Hundreds of thousands locally — the dedup uses a hash set, so it scales linearly with no size limit.

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Deploy this tool on Vercel · Ship faster with Cursor · Your static site on Cloudflare

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