Duplicate a List
Create multiple copies of a list. Runs entirely in your browser, so your data never leaves your device.
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Output
The result appears here as you type.
How to use Duplicate a List
- 1. Paste your list. Enter your items into the input pane, one per line. This works on any list you need repeated as a whole, one or more extra times.
- 2. Set the number of copies. Enter how many times the full list should repeat in Copies. Two copies gives you the list back to back twice, and so on.
- 3. Decide how items repeat. Turn on Repeat each item in place to duplicate each item right next to itself, rather than appending a whole second copy of the list after the first.
- 4. Copy the duplicated list. The output pane shows the repeated list according to your chosen mode. Copy the expanded result wherever it is needed.
When to use Duplicate a List
Duplicate a List repeats an entire list a set number of times, either as whole copies appended together or with each item repeated in place. It is a fast way to expand a short list without retyping it.
- Building test data with repeated rows. You need the same handful of test records repeated many times to simulate a larger dataset for a demo or load test, without manually copying and pasting the block.
- Doubling a raffle entry list intentionally. A promotion gives certain entrants two chances instead of one, and duplicating the whole list gives every name a second entry in the draw.
- Repeating each item for a paired layout. A design needs each label to appear twice in a row, such as printing address labels two to a sheet, which repeating each item in place produces directly.
- Generating a longer placeholder list from a short one. You have three sample items and need thirty for a mockup, so duplicating the list ten times as whole copies quickly reaches the length you need.
Examples
Two copies
Input
a b
Output
a b a b
Interleaved copies
Input
a b
Output
a a b b
About the Duplicate a List tool
Duplicate a List does its work locally, right in the browser. Create multiple copies of a list. There is no upload step, no queue and no account, and your data never travels over the network.
It belongs to the List Tools collection on EditSafely, a set of 114 small, focused List utilities that share the same instant, private workspace.
You can shape the output with 2 settings, including Copies and Repeat each item in place, and the result refreshes the moment you change one. 2 worked examples further down the page show exactly what the tool produces for real inputs.
Running locally also makes the tool fast and dependable: results appear as you type or drop a file, there is no server outage that can take it down mid-task, and confidential data can be processed without a second thought.
Frequently asked questions
Is Duplicate a List free to use?
Yes, it is completely free. All 2,658 tools on EditSafely work without an account, a subscription or usage limits.
Is it safe to paste sensitive or confidential data?
Everything happens locally. Your browser downloads the tool's code once, then does all the processing itself; nothing you enter is transmitted, stored or logged. You can even go offline after the page loads and it will still work.
How much text can I process at once?
There is no fixed limit. Because the work happens on your own device rather than on a shared server, the practical ceiling is your machine's memory, which comfortably handles inputs far larger than typical online tools allow.
Do I need to sign up or install anything?
No. The tool works in any modern browser on desktop, tablet or phone. There is no account to create, no extension to add and no software to install.
How do I use the result?
The output panel has a one-click copy button, and you can keep refining the input while you work; the result updates in place as you type.