Line Numberer
Add sequential line numbers to any text with custom start, separator, and zero-padding — runs 100% in your browser with no upload.
1. First line 2. Second line 3. Third line
🔒 Line numbers are added in your browser — nothing is uploaded.
What this tool does
Line Numberer prefixes every line of your text with a running number. You choose where the count starts, which separator sits between the number and the line (a period, colon, tab, or space), and whether numbers are zero-padded so they line up in a neat column. The numbered result updates live as you type and can be copied with one click.
When it is handy
Use it to number steps in an instruction list, label rows before pasting into a document, prepare ordered references, or make log lines easier to cite. Zero-padding keeps two- and three-digit numbers aligned, which is useful when the output goes into a fixed-width or monospaced context.
Frequently asked questions
Can I start numbering from something other than 1?
Yes. Set any start number and each following line increments by one. You can begin at 0, 100, or any whole number you like.
What does zero-pad to align width do?
It pads shorter numbers with leading zeros so every number is the same width. For example, across ten lines you get 01 through 10 instead of 1 through 10, keeping the text aligned.
Is any of my text uploaded to a server?
No. All numbering happens locally in your browser using JavaScript. Nothing you type is sent, stored, or uploaded anywhere.