Remove duplicate lines

• Remove duplicates. Every line is kept once, in its original order. By default the first occurrence stays; turn on Keep the last occurrence to keep the last one instead, which is useful when later lines are newer versions.
• Only the duplicated lines. Shows each line that appears more than once, listed once. Good for finding double entries.
• Only lines that appear once. Shows the lines that have no duplicates at all.

Example list: apple, pear, plum, apple, (blank), peach, Pear

Mode	Result (ignore case on)
Remove duplicates	apple, pear, plum, peach
Only duplicated lines	apple, pear
Only lines that appear once	plum, peach

The note under the result shows how many lines were kept and how many distinct lines were repeated.

Whether two lines count as duplicates depends on the settings:

• Ignore case (on by default): Apple, APPLE and apple are the same. The output keeps the spelling of the occurrence that stays.
• Trim spaces at the start and end of lines (on by default): apple and apple␣␣ are the same. Spaces inside a line still matter.
• Remove empty lines (on by default): blank lines are dropped instead of being treated as a line that can repeat.

For email lists, turn on both ignore case and trimming: email addresses are not case-sensitive in practice, and stray spaces are a common copy-paste artifact. For codes and IDs where case matters, such as some product SKUs or passwords, turn ignore case off.

If two lines look identical but are not removed, they differ in a way you can't see:

• Invisible characters such as zero-width spaces or a non-breaking space instead of a normal one. Clean them with remove extra spaces first.
• Different quotes or dashes, like a curly apostrophe (’) in one line and a straight one (') in the other.
• Accents: José and Jose are different strings. If they should match, run the list through remove accents first.
• Spaces inside the line, for example a double space between first and last name.

After normalizing, paste the list back and the duplicates will be caught.

• Email and contact lists. Merge signups from several sources and remove the people who appear twice.
• Keyword lists. Combine research from different tools without repeats.
• Log files. Collapse repeated messages to see the distinct events.
• Inventory and product codes. Find SKUs entered twice with Only the duplicated lines.
• Survey answers and tags. Get the list of distinct values.

To compare two separate lists, for example old customers vs. new signups, use compare two lists, which shows what's in both and what's only in one. To find repeated words rather than whole lines, use remove duplicate words.

Copy a single column from Excel or Google Sheets, paste it here, remove duplicates and paste the result back. Each cell becomes one line and the order is preserved, so the result lines up with what you expect.

If you need to dedupe based on one column of a multi-column table, first pull out that column with extract columns. After deduplication you can sort the result with sort lines.

Lists with hundreds of thousands of lines work fine. Processing happens in your browser, so private lists never leave your computer.