Remove Duplicate Lines Online
Lists copied from spreadsheets, databases, and text files almost always carry repeated entries. Keyword lists, email addresses, log entries, product SKUs, all of them accumulate duplicates over time. Paste your text here to strip repeated lines and keep only unique ones, with options for case sensitivity and whitespace handling. Nothing is uploaded.
How it works
Paste your text into the left panel. Each line is compared against the others based on your chosen settings. Lines identified as duplicates are removed and the cleaned output appears in the right panel ready to copy.
The options explained
Keep first occurrence removes every repeated line except the first time it appears. The original order of your list stays intact. This is the right choice when the sequence of entries matters and you want to preserve how the list was originally structured.
Keep last occurrence works the opposite way, removing all earlier copies and keeping the final one. Useful when your list was built over time and the most recently added entry is the one worth keeping.
Remove all occurrences deletes every line that appears more than once, including the original. Nothing survives if it has a repeat anywhere in the text. Use this when you only want lines that are genuinely unique and any repeated entry is considered invalid data.
Case sensitivity controls whether “Apple” and “apple” are treated as the same line or two different ones. With case-sensitive matching on, they are kept as separate entries. With it off, they are treated as duplicates and one gets removed. For email address lists and domain lists, turning case sensitivity off is usually the right call since email addresses are not case-sensitive in practice.
Trim whitespace before comparing ignores leading and trailing spaces when checking for matches. A line with a trailing space and the same line without one are treated as duplicates. This catches the kind of subtle differences that come from spreadsheet exports or copy-paste inconsistencies. If there is heavier whitespace noise throughout the text, running it through the remove extra spaces tool first gives you cleaner input before deduplication.
Where duplicate lines come from
Spreadsheet and database exports are the most common source. Merging two tables, appending rows from different exports, or combining data from multiple team members all produce repeated entries that are not obvious until you look at the raw text.
Keyword lists grow duplicates over time. Adding new terms across multiple sessions without a deduplication step means the same keyword gets added again, sometimes with slightly different capitalisation or trailing spaces that make the repeat hard to spot manually.
Log files repeat entries when the same event fires more than once. Stripping those repeated lines down to unique occurrences makes the log much easier to read and process.
Copy-pasting from multiple sources into a single document almost always produces repeats, particularly with lists of URLs, names, or product codes gathered from different places.