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How to Use Duplicate Lines: Complete Guide (2026)
Learn how to use duplicate lines free online — no signup, no download. Follow our step-by-step guide below.
What is Duplicate Lines?
Duplicate lines in text N times. Supports two modes: concatenate (Original + Copy + Copy) or interleave (Original, Copy, Original, Copy). Option to reverse copies. Useful for creating repeated content, test data, and text patterns.
- 100% browser-based — no data uploaded to servers
- Free to use — no signup required
- Instant results — no waiting
- Works on all devices — mobile, tablet, desktop
How to Use Duplicate Lines: Step-by-Step
- 1
Paste your text
Type or paste text with multiple lines.
- 2
Set number of copies
Enter how many times to duplicate (2 = original + 1 copy).
- 3
Choose mode
Select 'Concatenate' to append copies, or 'Interleave' to alternate.
- 4
Duplicate
Click Duplicate. The duplicated text appears in output.
Common Use Cases
Test data generation
Create repeated test data for software testing.
Content creation
Create repeated patterns for text art or formatting.
Data expansion
Expand small datasets by duplicating entries.
FAQ About Duplicate Lines
What is 'Concatenate' mode?
Concatenate mode puts all copies together: Original + Copy + Copy + ...
What is 'Interleave' mode?
Interleave mode alternates: Original, Copy, Original, Copy, ...
Can I reverse the copies?
Yes. Enable 'Reverse copies' to reverse the order of duplicated lines.
Ready to Try Duplicate Lines?
No signup. No download. 100% free.