Line Deduper

How it works

The tool splits your text into lines and tracks which lines it has already seen. When 'Case-insensitive' is on, comparisons ignore letter case. When 'Preserve original order' is off, the remaining unique lines are sorted alphabetically instead of kept in their original positions.

Benefits

• Removes exact and case-insensitive duplicate lines in one pass
• Shows a live count of total, unique, and removed lines
• Optional alphabetical sort of the deduplicated result
• Runs entirely offline with no upload

Use cases

• Cleaning a list of email addresses before a mail merge
• Removing repeated tags or categories from exported data
• Deduplicating a list of URLs or file paths
• Consolidating survey responses or log lines for review

Best practices

• Trim whitespace first if lines differ only by leading or trailing spaces
• Enable case-insensitive matching for user-entered tags or names
• Check the removed-line count to confirm the cleanup did what you expected
• Keep original order when line sequence carries meaning, such as a changelog

Common mistakes

• Expecting whitespace-only differences to be treated as duplicates automatically
• Assuming the last occurrence of a duplicate is kept instead of the first
• Forgetting that disabling 'preserve order' sorts the output alphabetically
• Deduplicating before sorting when the order of first occurrence matters for context

Privacy

Deduplication happens entirely in your browser using JavaScript. ToolHub does not receive or store the lines you process here.