Remove Duplicate Lines — Free, No Upload, Instant

About Remove Duplicate Lines

Duplicate lines creep into text constantly. You merge two exports of email addresses, concatenate log files, paste a column from a spreadsheet, or build a list from several sources, and suddenly the same entries appear two or three times. Scanning for repeats by eye is unreliable, and sorting to group them only solves part of the problem. This tool removes duplicate lines from any block of text in one pass, keeping the first occurrence of each unique line and preserving the original order of everything that survives.

Two options control what counts as a duplicate. "Ignore case" treats lines that differ only in capitalization as the same, so Apple and apple collapse into a single entry, which is useful for case-insensitive data like email addresses, tags, or country names. "Trim whitespace" strips leading and trailing spaces before comparing, so a line with an accidental trailing space is recognized as identical to its clean twin. You can combine both toggles or leave them off for a strict, character-for-character comparison.

After processing, the tool reports how many duplicate lines it removed, which is a quick sanity check that the cleanup did what you expected. The result appears in a scrollable monospace panel so long lists stay readable, and a Copy button puts the deduplicated text on your clipboard. Because the first occurrence is always kept and order is otherwise untouched, you do not lose the sequence of a list that was deliberately ordered.

Typical uses include cleaning mailing lists, deduplicating keyword or tag collections, tidying CSV columns, consolidating merged logs, and preparing word lists. It runs entirely in your browser, so pasting a sensitive list of addresses or records never sends that data anywhere.