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Remove duplicate lines from text while keeping first-seen order. Case and trim options.
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Removes duplicate lines from pasted text, keeping the first occurrence and preserving original order. Optional case-sensitive comparison and per-line whitespace trimming.
Cleaning up exported lists (emails, SKUs, log files) almost always starts with deduping. Doing it by hand is impossible past a few hundred rows; generic spreadsheets force you to import, dedupe, and export back.
This tool is part of the DevStackIO platform — a collection of free online developer tools from DevStackIO. Browse more free developer resources on DevStackIO.
Data analysts cleaning CSV columns, developers deduping log lines or URL lists, marketers cleaning email lists, and anyone with a long pasted list.
Paste lines into the input textarea
Choose case sensitivity and trimming
Review the kept/removed counts
Copy the result with one click
apple\nBanana\napple\nCherry\nbanana → 3 kept, 2 removed (case-insensitive)Same input with case-sensitive ON → 4 kept, 1 removedQ: Does it sort? A: No
order is preserved exactly as first-seen.
Q: How are blank lines treated?
A: Blank lines pass through; only non-blank lines are deduplicated.
Q: CRLF or LF?
A: Both are handled; the output uses the input's line-ending style.
Authoritative specifications, standards, and in-depth reading for Duplicate Line Remover.
3 kept · 2 removed
First occurrence wins; order is preserved. Blank lines pass through unchanged. 100% client-side.
Sort lines alphabetically and remove duplicates. Use when cleaning lists; for comparing two texts use text-diff-visual. Input: text lines ≤10MB. Returns sorted unique lines. 100% client-side.
Find and replace text with literal, regex, and case-insensitive modes. Shows replacement count.
Normalize line breaks to LF (Unix/Mac) or CRLF (Windows), or remove them entirely.
Count words, characters, and sentences. Get reading time and Flesch score as you type.
Preview rendered Markdown without editing. Use for quick read-only preview; for editing use markdown-editor, for HTML output copy use markdown-to-html. Input: Markdown ≤10MB. Returns rendered HTML preview. 100% client-side.
Generate URL slugs from titles with lowercase rules. Use as default slug tool; slugify-string is a noindex alias. Input: text ≤10MB. Returns slug string. 100% client-side.
Visual side-by-side diff for two texts with char-level highlights. Use as default diff tool; for similarity score use string-comparison, for JSON use json-diff. Input: two texts ≤10MB. Returns visual diff. 100% client-side.
Obfuscate strings with masking and reversible transforms. Use when hiding PII in demos; for hashing use hash-generator. Input: text ≤10MB. Returns obfuscated text. 100% client-side.