About the Duplicate Line Remover
Duplicate Line Remover cleans up lists, logs and datasets by stripping out repeated lines. It supports case-sensitive or case-insensitive matching, trimming whitespace before comparison, choosing whether to keep the first or last occurrence, and optional sorting or blank-line removal, so you get exactly the unique list you need.
How to use it
- 01Paste your list of lines into the input panel.
- 02Choose whether matching should be case-sensitive and whether lines should be trimmed first.
- 03Decide whether to keep the first or last occurrence of each duplicate.
- 04Copy or download the deduplicated result, and check the summary for how many lines were removed.
Features
- Case-sensitive or case-insensitive duplicate detection
- Optional trimming of leading and trailing whitespace before comparison
- Keep-first or keep-last occurrence strategy
- Optional alphabetical sorting and blank-line removal, with a duplicate-count summary
Practical examples
Email list cleanup
Paste a list of email addresses collected from multiple sources and remove exact or case-insensitive duplicates.
Log line deduplication
Strip repeated log entries to see only the distinct messages that occurred.
Limitations
- Duplicate detection compares whole lines only; it cannot detect near-duplicates that differ by a single character.
- Very large inputs are processed in memory in the browser, so extremely large files may be slow on low-memory devices.
Privacy
All deduplication logic runs locally in your browser; your list is never sent to a server.
Read the full privacy policy for how the site as a whole handles data.
Frequently asked questions
What happens to blank lines by default?
Blank lines are kept unless you enable the 'remove blank lines' option, and duplicate blank lines are deduplicated like any other line.
Can I keep the last occurrence instead of the first?
Yes, toggle 'keep last occurrence' to preserve the final instance of each duplicate rather than the first.
Does sorting happen before or after deduplication?
Deduplication happens first, and sorting is applied afterward to the resulting unique lines.