Remove Duplicate Lines — Free Online Tool

Remove Duplicate Lines takes a block of text and returns it with repeated lines collapsed to a single occurrence, optionally stripping blank lines and trimming surrounding whitespace at the same time. It is a small operation that is genuinely tedious by hand once a list runs past a few dozen lines.

The detail that catches people out is what counts as "duplicate". Two lines that look identical on screen can differ by a trailing space, a tab, or a capital letter, and a strict comparison treats them as distinct. Trimming whitespace before comparing catches the invisible cases; whether "Ahmed" and "ahmed" should be treated as the same entry depends entirely on your data, which is why the case-sensitivity choice is yours to make rather than being applied silently.

The lists people actually clean here tend to be email addresses exported from two overlapping sources, keyword lists merged from several research tools, URL lists for a redirect map, CSV columns pasted out of a spreadsheet, and log output where the same line repeats hundreds of times around the moment something broke.

Everything runs in your browser, so a list of customer emails or internal URLs is processed on your own machine and never uploaded.

Our Remove Duplicate Lines is completely free to use with no signup required. For this tool, processing runs in your browser — your files and data stay on your device and are not uploaded to our servers.

Whether you are a developer, designer, student, or business owner, this tool is designed to save you time and make your workflow more efficient. Bookmark this page to access it whenever you need it — it will always be free.