Remove Duplicate Lines
Remove duplicate lines from any text — logs, email lists, CSVs, keywords, and more. 100% client-side.
16
Total lines
10
Unique lines
6
Removed
95 chars
57 chars
🔒 100% private: All processing happens in your browser. Your text never leaves your device.
About Remove Duplicate Lines
Duplicate lines are everywhere: log files with repeated errors, email lists with the same address multiple times, keyword lists, CSV exports, and copy-pasted data. Removing them manually is slow and error-prone — especially for hundreds or thousands of lines. This tool removes duplicate lines instantly, with flexible options: keep the first or last occurrence, treat lines as case-insensitive, trim leading/trailing whitespace before comparing, ignore empty lines, and optionally sort the output. You also see a summary — total lines, unique lines, duplicates removed. All processing happens in your browser; your data is never uploaded.
How It Works
- Paste your text (one item per line) into the input box.
- Choose options: keep first/last, case-insensitive, trim whitespace, ignore empty.
- See the deduplicated result instantly, along with a summary of duplicates removed.
- Copy the result or download it as a .txt file.
✨ Key Features
- ✓Remove duplicate lines (keep first or last occurrence)
- ✓Case-insensitive comparison (treat "Hello" and "hello" as same)
- ✓Trim whitespace before comparing (ignore leading/trailing spaces)
- ✓Ignore empty lines option
- ✓Alphabetical sort option (ascending or descending)
- ✓Live deduplication as you type
- ✓Summary stats: total, unique, duplicates removed
- ✓Copy result to clipboard
- ✓Download result as .txt
- ✓100% client-side — no data sent to any server
🎯 Common Use Cases
- →Cleaning up email lists before sending a campaign
- →Removing repeated errors from log files
- →Deduplicating keyword lists for SEO
- →Cleaning CSV or TSV exports
- →Removing repeated URLs from a list
- →Deduplicating user-generated content
- →Combining lists from multiple sources
- →Preparing unique test data
💡 Advanced Tips & Pro Insights
- ▸For email or URL lists, enable "Trim whitespace" and "Case-insensitive" — real-world lists often have inconsistent spacing and capitalization.
- ▸"Keep last" is useful when later entries are the most recent or authoritative (e.g., updated values).
- ▸If your list has leading/trailing spaces, "Trim whitespace" treats "apple" and "apple " as duplicates.
- ▸Sorting after deduplication makes it easier to review the result — but if order matters (e.g., timeline), leave sorting off.
- ▸For very large lists (100k+ lines), the browser may take a few seconds. Split into chunks if needed.
Frequently Asked Questions
Is this tool free?▾
Yes, this duplicate line remover is completely free with no signup, email, or usage limits.
Is my data safe?▾
Yes, 100% safe. All processing happens in your browser. Your text is never uploaded to any server.
What is the difference between "Keep first" and "Keep last"?▾
"Keep first" preserves the first occurrence of each unique line and removes later duplicates. "Keep last" does the opposite — it keeps the last occurrence. Use "keep first" when order matters and you trust the first entry; use "keep last" when later entries are more recent.
What does "Case-insensitive" do?▾
When enabled, "Hello" and "hello" are considered the same line (one is removed). Useful for cleaning lists where capitalization is inconsistent.
What does "Trim whitespace" do?▾
When enabled, leading and trailing spaces/tabs are removed before comparing lines. So "apple" and "apple " are treated as duplicates.
Does it remove blank lines?▾
Optionally. Enable "Ignore empty lines" to remove all blank lines from the output — useful for cleaning up lists that have been copy-pasted from different sources.
Can I sort the result?▾
Yes. Choose "Sort ascending" or "Sort descending" to alphabetize the output. Otherwise the original order of unique lines is preserved.
Does it handle very large files?▾
Yes, up to browser memory limits. For very large files (1M+ lines), consider a command-line tool like sort -u or awk.