Find duplicate lines in multi-line text and keep only the first occurrence of each. Compare case-insensitively or after trimming leading/trailing whitespace.
Email lists, log files, spreadsheet exports, and keyword lists merged from multiple sources often end up with the same line repeated. Hunting duplicates by hand is tedious and error-prone. This tool compares line by line, keeps the first occurrence of each, and removes every repeat in one pass.
Removing duplicates doesn't re-sort anything — the surviving lines keep the exact order they first appeared in. That makes it safe for lists where original ordering matters, like "first registered email wins".
Turn on "Ignore case when comparing" to treat "Apple" and "apple" as the same entry. If lines that are logically identical differ only by trailing whitespace, "Trim whitespace before comparing" strips that noise before deduplicating so it catches the true duplicates.