What happens when you run this tool
Add a prefix to every list item.
This kind of tool is most helpful when manual editing would be slower, more error-prone, or too opaque to verify quickly.
Where the new content is inserted
Add List Prefix inserts new content into each relevant items. Position matters here. Adding something before a line, after a line, or around a value can change how the output is read downstream, even when the original content stays intact.
List tools usually treat each line or separator-delimited value as a discrete item, so separators and blanks affect the result.
This tool is deterministic: the same input and the same settings produce the same output every time. All processing happens in your browser, so your input stays on your device during the transformation.
Where this tool earns its keep
Add tags to list items.
Prefix items for display.
Prepare lists for scripts.
Examples
Quick before and after
Input
Add List Prefix input:
Email: john.doe@example.com
Status: active
Output
Add List Prefix output:
Email: john.doe@example.com
Status: active
Added markers become part of the output
Input
alpha
beta
Settings
Suffix: .
Output
1. alpha
2. beta
Spacing is controlled by the prefix or suffix values.
Input expectations and common surprises
Insertion tools are literal. If spacing around the added content matters, include that spacing in the prefix, suffix, or inserted text itself rather than assuming the tool will add it for you.
For deterministic tools, the same input and the same settings should reproduce the same result. If not, the input likely changed in a small but meaningful way.