Text tools
Number Lines
Add sequential numbers while keeping your text intact.
Processed in your browser
Each included line becomes Prefix + number + Separator + original text. Start and Increment accept signed whole decimal numbers; zero or negative increments are allowed.
Choose your options, then number lines.
Editor text uses LF line endings. Downloads use UTF-8.
How to use
- Set your options
Choose the first number, increment and label format. Decide whether to number blank lines.
- Add your text
Paste text or open a UTF-8 file, then choose Number lines. File content appears when processed.
- Get your result
Copy or download your numbered text. Use as input lets you build on the result.
Numbering rules and common questions
Will blank lines be numbered?
Yes, by default. A blank line is empty or contains only ASCII spaces and tabs. Uncheck Number blank lines to leave these lines unchanged without advancing the number. A final line ending does not create an extra line. Empty input produces empty output.
Are large numbers exact? How does padding work?
Start and Increment use exact integer arithmetic, including values beyond JavaScript’s safe Number range. Enter decimal digits with an optional + or − sign (use the keyboard hyphen for minus), not fractions or exponent notation. Surrounding whitespace is ignored. Minimum digits adds leading zeros, excluding the minus sign: −2 with three digits becomes -002. Numbers are never truncated. Use Prefix and Separator for literal text around each number; the default separator is a dot and a space.
What happens to my text and line endings?
Letters, Unicode, emoji, combining marks and whitespace remain intact. Lines are separated by CRLF, LF, CR, Unicode line separator or paragraph separator. UTF-8 file downloads preserve each ending and a leading BOM before the first number. File names and MIME types do not restrict valid UTF-8 input; malformed UTF-8 gives an error. The editor and displayed result normalize CRLF and CR to LF. Editing or using the result as input switches to that editor behavior; clipboard applications may also adapt endings. Downloads are plain UTF-8 text.
Is my text private? Can I cancel?
Processing and file decoding run in your browser. Text and file names are not uploaded, logged or saved in browser storage. Cancel stops processing and keeps your input; Reset clears input, results and settings. There is no fixed text-length or digit-length cap. Padding must be a positive whole safe integer; actual browser number, string and memory capacity still applies, and failures are reported. Very large editor previews can be less responsive.