Skip to main content

Duplicate Remover

Free online tool to remove duplicate lines from text and keep only unique lines.

⚙️ Options

📝 Input Text

📊 Statistics

Total Lines0
Unique Lines0
Removed Lines0

✨ Result (Unique Lines)

Removes duplicate lines from your text. Use "Case Sensitive" to distinguish between uppercase and lowercase. Use "Sort Output" to alphabetically sort the results.

Key Features​

  • Remove Duplicate Lines: Automatically detect and remove identical content lines
  • Case Sensitivity: Choose whether to distinguish case
  • Sort Option: Optionally sort results alphabetically
  • Real-time Statistics: Display total lines, unique lines, and removed lines count
  • Preserve Order: Maintain original order while removing duplicates (when not sorting)

How to Use​

Basic Usage​

  1. Enter text in the input area (one per line)
  2. Duplicates are automatically removed and results displayed
  3. Click "Copy" button to copy results to clipboard

Option Settings​

  • Case Sensitive: When checked, treats "Apple" and "apple" as different
  • Sort Output: When checked, sorts results alphabetically

Use Cases​

1. Clean Email List​

Input:
user1@example.com
user2@example.com
user1@example.com
user3@example.com

Output:
user1@example.com
user2@example.com
user3@example.com

2. Clean Keyword List​

Useful for removing duplicate keywords in marketing or SEO work.

Input:
react
javascript
react
vue
javascript
angular

Output:
react
javascript
vue
angular

3. Clean File Paths​

Use when removing duplicate paths from log files or scripts.

Input:
/home/user/docs
/home/user/downloads
/home/user/docs
/home/user/pictures

Output:
/home/user/docs
/home/user/downloads
/home/user/pictures

4. Data Cleanup​

Use when removing duplicate items from CSV files or databases.

Option Details​

Case Sensitive​

When Unchecked (default)​

Ignores case when determining duplicates.

Input:
Apple
APPLE
apple
Banana

Output:
Apple
Banana

When Checked​

Distinguishes case when determining duplicates.

Input:
Apple
APPLE
apple
Banana

Output:
Apple
APPLE
apple
Banana

Sort Output​

When Unchecked (default)​

Maintains original order (first occurrence order).

Input:
Zebra
Apple
Banana
Apple

Output:
Zebra
Apple
Banana

When Checked​

Sorts results alphabetically.

Input:
Zebra
Apple
Banana
Apple

Output:
Apple
Banana
Zebra

Statistics​

The tool displays three statistics in real-time:

  • Total Lines: Total number of lines entered
  • Unique Lines: Number of lines remaining after duplicate removal
  • Removed Lines: Number of duplicate lines removed

Practical Tips​

1. CSV File Processing​

When removing duplicates from a specific column in a CSV file:

  1. Copy the column from Excel or spreadsheet
  2. Paste into this tool
  3. After removing duplicates, paste back

2. Log Analysis​

Useful for finding unique IP addresses or users in server logs.

3. Code Cleanup​

Can be used to remove duplicates from import statements or dependency lists.

4. Bulk Data Processing​

Can quickly process thousands of lines.

Algorithm Explanation​

This tool uses JavaScript's Set data structure to efficiently remove duplicates:

const seen = new Set();
lines.forEach((line) => {
  const key = caseSensitive ? line : line.toLowerCase();
  if (!seen.has(key)) {
    seen.add(key);
    uniqueLines.push(line);
  }
});

Time complexity: O(n) - Very efficient!

Frequently Asked Questions​

Q: How are blank lines handled?​

Blank lines are treated the same as regular lines. If there are multiple blank lines, only one will remain.

Q: Do leading/trailing spaces affect duplicate detection?​

Yes. "Apple" and " Apple " (with leading space) are treated as different. To remove spaces, use the Whitespace Remover tool first.

Q: How many lines can be processed?​

Theoretically unlimited, but depends on browser memory. Generally, tens of thousands of lines are processed without issues.

Q: How does the sort option work?​

Uses JavaScript's localeCompare for natural alphabetical sorting. Korean is also sorted in alphabetical order.

🔗 Try These Next​

💬 Was this tool helpful?​

Feel free to send us your feedback or suggestions anytime!

Performance​

  • Processing Speed: Processes 10,000 lines in under 1 second
  • Memory Efficiency: Optimized with Set data structure
  • Real-time Processing: Results displayed immediately upon input

Privacy​

This tool operates entirely on the client side. Your input data is never sent to a server and is processed only in your browser.