Remove Duplicate Lines

About this calculator

This tool cleans a block of text by removing duplicate lines, comparing each line to the ones seen before it and keeping only the first occurrence, so the original order of the remaining lines is preserved rather than sorted or shuffled. It works purely on exact line matches, so two lines that differ by even a trailing space or a capital letter are treated as different.

It is used by developers cleaning up log files, CSV exports or lists of URLs and email addresses that have accumulated repeated entries, and by anyone merging two lists — contacts, tasks, keywords — who wants a single clean version without manually scanning for repeats. It's a routine step before importing a list into a spreadsheet or database where duplicate rows would cause errors or skew counts.