Remove Duplicate Lines — Deduplicate Text Online

What is Remove Duplicates?

A deduplication tool takes a list of lines and returns a version with duplicates collapsed. It sounds trivial, but real-world lists have subtle traps: leading/trailing whitespace that makes two lines 'look' the same but hash differently, mixed casing where 'Apple' and 'apple' should sometimes count as duplicates and sometimes not, blank lines from copy-paste, and hidden characters like BOM or non-breaking spaces. This tool exposes all of those as toggles, preserves the first-occurrence order (so you can trust the output), and shows a frequency panel so you can see which lines were repeated and how many times.

How to remove duplicate lines online

1. 1Paste your list — one item per line.
2. 2Toggle case sensitivity, whitespace trimming, and empty-line handling to match how you define 'duplicate'.
3. 3Choose 'Keep first' (default) to return each unique line once, or 'Keep only uniques' to return only lines that appear exactly once.
4. 4Copy the deduplicated output. Check the 'Duplicate frequencies' panel to see which lines were the most repeated.

Use Cases

Tips & Best Practices

• ▸For case-insensitive dedup, the tool keeps the first occurrence's original casing — 'Apple' before 'apple' means 'Apple' survives.
• ▸'Trim each line' is critical for CSV-like data where trailing spaces sneak in — otherwise 'foo' and 'foo ' count as different.
• ▸The frequency panel is capped at 20 lines to keep the UI responsive; for full counts, export the output and count with sort | uniq -c in a terminal.
• ▸This is line-level dedup — it doesn't understand JSON, CSV columns, or fuzzy similarity. For structured or fuzzy dedup use a dedicated data-cleaning tool.