Free Duplicate Line Remover
Remove repeated lines without sorting them, then inspect the exact source line numbers and occurrences that were removed.
Browser-local text utility
Runs in your browserEnter your text
Choose the exact operation before creating an output.
Editable plain text · up to 200,000 characters · text is never included in a share URL
0 words0 characters0 lines0 paragraphs
Runs in your browser. The operation is deterministic except an unseeded line shuffle. No source text, result text, seed, search term or comparison content is sent to ScholarTool services.
Current result
Duplicate Line Remover results
Every visible metric and finding below comes from the current inputs and result.
Complete an operation to begin
The dashboard will show only real output and observed changes.
0 words0 characters0 lines0 paragraphs
Editable output · these counts and the After card recalculate after manual edits
Detailed findings
Use this result
Result utilities
Exports use the current editable result or comparison.
What is line deduplication and what does this Duplicate Line Remover do?
Line deduplication compares complete text lines using the rules you choose and retains one occurrence from each matching group. This tool preserves the order of retained lines and never sorts or rewrites their contents.
How to use Duplicate Line Remover
Paste one record or value per line.
Choose case sensitivity, trimmed comparison, keep-first or keep-last, and blank-line behavior.
Remove duplicates and inspect the before/after line totals.
Review the removed-line table before copying or exporting the result.
Key features
- Keep-first and keep-last selection
- Case-sensitive or case-insensitive keys
- Optional leading/trailing whitespace trimming for comparison only
- Explicit duplicate blank-line handling
- Removed-line report with original and matching line numbers
Input guide
Every physical line is a record, including a trailing empty line. Trim for comparison affects only the matching key; the retained line keeps its original content. Preserve Blank Lines exempts empty or whitespace-only lines from deduplication.
How to understand your results
Lines Before and Lines After are physical line counts. Duplicates Removed equals the rows excluded. Unique Lines is the retained count, and the report identifies each removed source line and the retained occurrence it matched.
Worked example
Example input
Alpha beta alpha Beta
How to read it
With case-insensitive, trimmed comparison and Keep First, “ alpha ” matches Alpha and Beta matches beta, leaving the first two lines in their original order.
Common use cases
- Deduplicate email, keyword or identifier lists
- Remove repeated bibliography or log entries
- Keep the last revision of repeated line keys
- Clean blank-line duplication without sorting content
Duplicate Line Remover guidance and best practices
- Choose case-insensitive matching only when capitalization is not meaningful.
- Use trimmed comparison to ignore accidental outside spacing while preserving the retained source line.
- Export the removed-line report when the decision needs an audit trail.
Limitations, assumptions and cautions
- The tool compares whole lines, not semantic meaning.
- Unicode lookalikes and different normalization forms can remain distinct.
- Keep Last preserves the surviving lines’ original relative order, not group order by first appearance.
Privacy and processing
Runs in your browser.
Deduplication and reporting happen in the current browser. Source lines are never sent to an API or included in canonical links.
Continue this workflow
Related tools
These live canonical tools support a practical next step without duplicating this task.
Sort LinesOrder lines alphabetically, naturally, numerically or by length with stable locale-aware comparison and explicit blank-line handling.Randomize LinesShuffle complete lines with Fisher–Yates, browser cryptographic randomness by default, and an optional deterministic seed.Text CleanerRemove selected whitespace and formatting noise with independent cleanup options, editable output and a factual operation report.
Helpful answers
Duplicate Line Remover FAQs
Clear guidance for choosing and using the catalogue responsibly.
What counts as a duplicate line?
Two complete lines are duplicates when their comparison keys match under the selected case and trimming rules.
Does the tool preserve the original order?
Yes. It filters the existing sequence and never sorts the retained lines.
Can duplicate matching ignore capitalization?
Yes. Turn off Case Sensitive to compare locale-lowercased line keys.
Can leading and trailing spaces be ignored?
Yes. Trim for Comparison changes only the key; the kept line retains its original spacing.
What is the difference between Keep First and Keep Last?
Keep First retains the earliest occurrence in a group; Keep Last retains the latest occurrence.
Can duplicate blank lines be removed?
Yes. Disable Preserve Blank Lines to keep one matching blank line and remove later or earlier duplicates according to the keep mode.
Can I see how many duplicate lines were removed?
Yes. The dashboard and removed-line table report the exact count and source line numbers.
Does the text remain in my browser?
Yes. No list content leaves the browser.