🔢 Add Line Numbers

📝
Lines: {{ inputText.split('\n').length }} | Characters: {{ inputText.length }}
⚙️
🎨
Use {line} for line number and {text} for text content
🔧
📤 
{{ outputText }}
📊
Original Text:
Lines: {{ stats.original?.lines }}
Characters: {{ stats.original?.characters }}
Words: {{ stats.original?.words }}
Empty lines: {{ stats.original?.emptyLines }}
Result:
Numbered lines: {{ stats.result?.numberedLines }}
Skipped lines: {{ stats.result?.skippedLines }}
Final number: {{ stats.numbering?.finalNumber }}
Format: {{ stats.numbering?.format }}
👁️
{{ startNumber }}: Sample text line
{{ startNumber.toString().padStart(padding,'0') }}: Sample text line
{{ customFormat.replace('{line}', startNumber).replace('{text}','Sample text line') }}
⚠️ {{ error }}

ℹ️ About Add Line Numbers

Add Line Numbers prefixes each line of plain text with a sequential line number, creating stable references without changing the original line order. It is useful when you need editor-style line references for code snippets, logs, transcripts, procedures, legal drafts, or documentation excerpts.

Practical uses:

  • Code review: add line references to pasted source, stack traces, shell output, or configuration files.
  • Documentation: turn instructions, checklists, meeting notes, or policy text into numbered reference material.
  • Data cleanup: mark each record in a newline-delimited list before sorting, comparing, or sharing it.
  • Publishing: produce padded line numbers for examples that should align neatly in monospaced text.

Technical behavior:

  • Simple format outputs values such as 1: text, while padded format outputs values such as 001: text.
  • Custom format replaces {line} with the current number and {text} with the original line content.
  • Start Number and Increment control the sequence; both are normalized to positive integers.
  • Skip empty lines preserves blank lines without assigning or consuming a line number.
  • Padding Width is capped at 20 characters to keep output readable and predictable.

Examples: input lines alpha and beta become 1: alpha and 2: beta in simple mode. With padded width 3, they become 001: alpha and 002: beta. A custom template such as [L{line}] {text} produces [L1] alpha.

Line numbering follows the same general text-filtering idea as command-line utilities such as the POSIX nl utility and GNU Coreutils nl / cat options, adapted here for browser text editing with custom templates.

Privacy note: the interactive page applies numbering in your browser as you type. If you use the API example, send only text you are comfortable processing on the server.

API Usage Example:

POST /api/tools/text/add-line-numbers
Content-Type: application/json

{
    "text": "First line\nSecond line",
    "startNumber": 1,
    "increment": 1,
    "format": "simple",
    "customFormat": "{line}: {text}",
    "padding": 3,
    "skipEmptyLines": false
}
Ready