Duplicate Line Remover

Reference

How does duplicate line removal work?

This tool processes your text line by line and keeps only the first occurrence of each unique line. Duplicate detection uses a hash set for O(1) lookups, making it fast even for large texts with thousands of lines. The original order of lines is preserved (unless you enable sorting), and the tool shows exactly how many duplicates were removed.

Options explained

Case sensitive — when enabled (default), "Hello" and "hello" are treated as different lines. Disable to treat them as duplicates regardless of capitalization. Trim whitespace — when enabled (default), leading and trailing spaces/tabs are removed before comparison, so " hello " matches "hello". Sort output — alphabetically sort the unique lines in the output. Useful when you want a clean, organized list.

Common use cases

Data cleaning — remove duplicate entries from CSV columns, log files, or exported data. Email lists — deduplicate email addresses or contact lists before sending. Code cleanup — remove duplicate import statements, CSS rules, or configuration entries. SEO — deduplicate keyword lists or URL lists. Spreadsheets — clean up a column of data before importing back into Excel or Google Sheets.

Privacy

All text processing runs 100% in your browser. No data is sent to any server.