What is Line Number Adder?

Line Number Adder labels every line of your text with a sequential marker. Put it at the start or end of each line, and choose numbers, letters, or Roman numerals. Handy for code reviews, documentation, or any text where line references matter.

Number in 1, 2, 3 / A, B, C / a, b, c / I, II, III or i, ii, iii style. Pick a separator (dot, parenthesis, colon, tab, pipe, or your own), or write a custom format like [N] or /* N */ where [N] becomes the number. Put markers at the start or end of each line, set any starting value, pad with spaces to align or with leading zeros to a fixed width, and skip blank lines. Already have a numbered list? Switch to Remove mode to strip the numbers back out. Copy the result or download it as plain text.

How to use

1. Paste your text — code, logs, or any multi-line content — into the input area.
2. Pick how lines are labelled: numbers, letters, or Roman numerals; a separator or a custom [N] format; the position (start or end); the starting value; and padding.
3. Copy the numbered output or download it as a text file for sharing in emails, reports, or code reviews.

When to use

• Quoting specific lines from a server log in a Slack incident channel.
• Annotating a code snippet in a tutorial or blog post for line-by-line commentary.
• Building a numbered list of survey responses or interview transcripts.

Result

You need to reference specific lines from a server log during an incident review. Add line numbers so your team can quickly jump to 'line 47' or 'lines 112-118' in the discussion.

FAQ

Will the numbers throw off my code if I paste it back into an editor?

Yes. The numbers are part of the text now, so a compiler or interpreter will read them as syntax errors. Use the output for reference and discussion only, not as runnable source.

Can I start numbering at something other than 1?

Yes. Set the Start Number field to whatever you want, including negative values. Handy when you're quoting lines 240 through 260 of a file and the reader needs the original line numbers.

Why does padding matter?

Without padding, line 9 starts one character to the left of line 10, so everything past the separator shifts. With padding the numbers are right-aligned and your code stays in a tidy column.

Does the tool handle blank lines?

However you like. By default blank lines get numbered too. Turn on Skip empty lines and the tool keeps blank lines in place but only numbers lines with content — handy for code with separator gaps.

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