Add sequential line numbers to text

Attach sequential integer labels to physical lines with configurable origin, separator, width, and padding character.

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ToolLine Numberer
Input
Output
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Preview

How it works

CRLF or LF creates the row array, then a counter advances only for rows selected for numbering. Starting at 1 with ": " is the default, and width zero aligns labels to the digits in start + physical row count − 1.

  • Blank rows receive labels unless empty-line skipping is enabled.
  • Output reconstruction always joins rows with LF.

Worked example

Number Lines
Add sequential line numbers to a code snippet
Input
											function greet() {
  return "hello";
}
Output
												1: function greet() {
2:   return "hello";
3: }

When to use this

Bug reports label log excerpts, code-review comments identify pasted snippet rows, and poetry worksheets number physical lines.

Edge cases

  • When empty rows are skipped, they keep no label and do not consume the next sequence number.
  • A negative starting value includes its minus sign when automatic padding width is calculated.
  • CRLF source text leaves with LF line endings even though every visible row receives the intended label.