Duplicate Line Remover

The Duplicate Line Remover is a free online tool that removes duplicate lines from your text. It is useful for managing large data sets, cleaning up lists, and eliminating redundant information. If you need to find repeated words within individual lines instead of duplicate lines, try the Duplicate Word Finder.

To use the tool, simply paste your text into the provided field and on the right the tool will automatically process your text and provide a version free of any duplicate lines.

The Duplicate Line Remover can handle large data sets efficiently. For best performance, keep text under 50,000 lines at a time.

The tool processes your text line by line and checks each line against a set of lines it has already seen. The first occurrence of each line is kept in its original order, and any later repeats are removed from the final output. If your data is numerical, the Number Sorter can arrange values in order before you check for duplicates.

Yes, after the tool has removed the duplicate lines, you can download the output in a text file or copy it directly to your clipboard for immediate use

By default, the tool performs case-sensitive comparison: Apple and apple are treated as different lines and both are kept. If your data uses inconsistent capitalization and you want to treat them as duplicates, convert all lines to the same case first using the uppercase or lowercase tool, then run the deduplication.

Input:

jane@example.com
john@example.com
Jane@example.com
sarah@example.com
john@example.com

Output (case-sensitive, default):

jane@example.com
john@example.com
Jane@example.com
sarah@example.com

Note that jane@example.com and Jane@example.com are kept as separate entries because the capitalization differs. In most email systems these resolve to the same inbox. Convert to lowercase first before deduplicating if you want these treated as one entry.

If you need to deduplicate lines as part of a larger workflow rather than manually:

• Excel / Google Sheets: Data > Remove Duplicates
• Command line (Mac/Linux): sort -u filename.txt (sorts and deduplicates simultaneously)
• Command line (any OS): sort filename.txt | uniq > output.txt
• SQL: SELECT DISTINCT column FROM table
• Python: list(dict.fromkeys(lines)) preserves insertion order while deduplicating

Yes. The tool keeps the first occurrence of each line and removes subsequent duplicates, preserving the order of the remaining lines.

Each line is trimmed of leading and trailing whitespace before comparison, so a line with extra spaces and the same line without them are treated as duplicates. The comparison is case-sensitive, so "Hello" and "hello" are kept as separate lines.

• Remove Line Breaks - Clean up line break formatting
• Word Frequency Counter - Analyze word frequency in text
• Alphabetical Sorter - Sort lines alphabetically
• Find and Replace - Search and replace text patterns
• Whitespace Remover - Remove extra whitespace from text