Add Line NumbersAdd sequential line numbers to each line of text.
Add Line Numbers
Add sequential line numbers to each line of text.
Paste Text
Enter the text you want to add line numbers to.
View Numbered Text
See each line prefixed with its sequential line number.
Copy Result
Copy the numbered text for documentation or sharing.
What Is Add Line Numbers?
This tool adds sequential line numbers to each line of text, making it easy to reference specific lines in documents, code snippets, or data files. Line numbering is essential for code reviews, documentation, error reporting, and any context where you need to refer to specific positions in a text. The numbers are formatted with consistent padding for alignment and use a customizable separator between the number and the line content.
Why Use Our Add Line Numbers?
- Add line numbers in one click
- Consistent padding for aligned output
- Essential for code snippets and documentation
- Makes line referencing easy in reviews
- Handles any text content
Common Use Cases
Code Documentation
Number code lines for reference in documentation, tutorials, and code reviews.
Error Reporting
Add line numbers to logs or output for easier error location reporting.
Legal Documents
Number lines in legal documents for precise cross-referencing.
Teaching Material
Number lines in example text for classroom discussion and annotation.
Technical Guide
Line numbering splits input on newlines, computes the number of digits needed for the highest line number (Math.ceil(Math.log10(totalLines + 1))), then pads each number with leading spaces for right-alignment. The separator (default ": ") is placed between the number and the line content. Numbering starts at 1 by convention (matching most text editors and IDEs). The padding ensures consistent alignment regardless of line count — a 100-line text uses 3-digit padding (e.g., " 1: ", " 10: ", "100: ").
Tips & Best Practices
- 1Use padded numbers for aligned output in monospaced fonts
- 2Line numbers make code snippets easier to discuss in reviews
- 3Remove line numbers with the Remove Line Numbers tool when done
- 4Numbered text is useful for creating study guides and annotated documents
- 5Most IDEs show line numbers natively — use this for sharing plain text
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Remove Line Numbers
Strip line numbers from numbered text to restore the original content.
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Text ToolsFrequently Asked Questions
QWhat number does it start from?
QAre the numbers padded?
QCan I change the separator?
QDoes it number blank lines?
QHow do I remove line numbers later?
About Add Line Numbers
Add Line Numbers is a free online tool from FreeToolkit.ai. All processing happens directly in your browser — your data never leaves your device. No registration required. No ads. Just fast, reliable tools.