ToolBirch

Add Line Numbers

Number every line with a custom start, separator and padding.Text Tools

Add Line Numbers

Prefix every line with a number. The start value, separator and zero-padding are all configurable.

About this tool

Numbering by hand falls apart past ten lines. This tool labels every line, aligns the numbers into a column with optional padding, and lets you pick the starting value — useful for referencing lines in reviews and logs.

How to use the Add Line Numbers tool

  1. Paste your text. Each line is numbered in order, including empty lines.
  2. Set the options. Start value, separator between the number and the line, and aligned padding.
  3. Copy the output. Take the numbered text straight into your document or issue.

Supported formats

Input

  • Plain text

Output

  • Numbered text

Inputs are validated before anything is processed. Invalid values and unsupported files are rejected with a clear error instead of failing silently.

Frequently asked questions

Are empty lines numbered too?

Yes, so the numbering stays aligned with the original line indices.

What does padding do?

Numbers are left-padded with spaces so all labels share a width, keeping the text column aligned.

Can I start from zero or another number?

Any start value of 0 or more works.

Is the separator configurable?

Four common separators are offered: period, colon, space and pipe.

Privacy

Everything you enter stays in this browser tab. There is no upload endpoint for tool inputs, no account, and no server-side copy of your text or files. Results are produced locally and disappear when you close the page.

No account is required and no file is ever uploaded. See the privacy policy for details about analytics and the limited data this site stores.

Known limitations

  • Numbers are prefixed, not gutter-rendered, so they become part of the text.
  • Only four separator presets; custom strings are not supported.
  • Tab characters inside lines are preserved as they are.

Related tools

Other free tools from the same collection.

Word CounterCount words, characters, sentences, paragraphs and reading time.Sort LinesSort list lines alphabetically, numerically or by length.Text DiffCompare two texts by line or word with a colour-coded diff.Remove Empty LinesStrip blank lines and tidy stray whitespace from pasted text.