Remove Duplicate Lines | Keep Unique Lines
Remove duplicate lines from any text while preserving the first occurrence and original order. Optional case sensitivity, trim-whitespace comparison, and A–Z sort—everything runs locally in your browser.
How to Use This Tool
- 1
Paste your lines (one item per line).
- 2
Choose options: case sensitivity, trim whitespace, A–Z sort.
- 3
Use Live mode for instant results or click Remove Duplicates in Manual mode.
- 4
Review stats and copy or download the unique lines.
Use Cases & Examples
Data Cleaning & Normalization
Normalize exports and CSVs by removing duplicate rows before analysis.
List Management
Deduplicate contact, email, or product lists to keep one of each item.
Code & Config Cleanup
Strip repeated imports/dependencies or config entries from code and manifests.
Log Analysis & Filtering
Filter repeated log messages to focus on unique events and signals.
How Deduplication Works
Each input line is checked once and stored in a Set to enforce uniqueness (average O(n) time).
Insertion order of the Set preserves the first occurrence and original sequence.
Optional alphabetical sort is applied after deduplication for predictable output.
All processing happens client-side for speed and privacy.
Frequently Asked Questions
Q.What if lines differ only by whitespace?
A. Yes—enable “Trim whitespace” to ignore leading/trailing spaces and treat lines that differ only by whitespace as duplicates.
Q.Is comparison case-sensitive or case-insensitive?
A. By default matching is case-insensitive; toggle “Case sensitive” to treat 'Apple' and 'apple' as different lines.
Q.Can it handle very large files efficiently?
A. Yes. A Set-based, O(n) algorithm handles hundreds of thousands to millions of lines efficiently on modern browsers (within memory limits).
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