How to Add Line Numbers to Text: Code, Logs, and Reference

When you need to refer to specific lines in a block of text — code snippets, log output, or lists — adding line numbers makes it easy for others (or future you) to say “see line 5” or “the error is on line 12”. A line number generator takes your text and prepends a number to each line, with options for start number, separator, and alignment.

Here’s when and how to use one, and what to expect from a good tool.

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What Is a Line Number Generator?

A line number generator takes text (one or more lines) and adds a line number at the start of each line. You get output like:

• 1 | first line
• 2 | second line
• 3 | third line

You choose how the numbers appear: start number (e.g. 1 or 100), separator (pipe, spaces, dot, or paren + tab), and whether to pad numbers so the text column lines up. Everything runs in your browser — no data is sent to a server.

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When to Use Line Numbers

• Code snippets — Add line numbers before pasting into docs, tutorials, or support replies so you can say “see line 5” or “the bug is on line 12”.
• Logs — Number log output for easier reference in tickets, discussions, or post-mortems.
• Lists — Number a list (tasks, items, steps) for reference without editing the original.
• Teaching — Provide numbered text for exercises (“answer referring to line 3”) or handouts.
• Data / CSV — Add row numbers to a column of values for debugging or reference.

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Options: Start Number, Separator, Padding

• Start number — The number assigned to the first line (default 1). Use a higher value if you’re continuing from a previous block (e.g. start at 100).
• Separator — What appears between the number and the line text. Pipe (|) is common and readable; spaces give a minimal gap; dot or paren + tab mimic editor styles (e.g. 1. or 1) with a tab). Choose based on where you’ll paste the result.
• Pad numbers — When on, line numbers are right-aligned (e.g. 1, 10, 100) so the text column lines up. When off, numbers are not padded. Padding is especially useful for long blocks (10+ lines).

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Is My Text Sent to a Server?

No. A good line number generator runs entirely in your browser. Your text never leaves your device — safe for code, logs, or sensitive content.

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Try the Line Number Generator

The Tooladex Line Number Generator lets you paste any text, set the start number and separator (pipe, space, dot, or paren + tab), and optionally pad numbers for alignment. Copy the result with one click. All processing in your browser — no account, no data sent to a server.