Add Line Numbers

The Add Line Numbers tool is a free online utility that prefixes every line of your text with a sequential number. As soon as you paste your content each line receives its own label, turning a plain block of text into a numbered list that is easy to reference, review and discuss with others.

It is ideal for teachers preparing exercises, reviewers referencing specific lines of code or documents, and anyone building an ordered checklist from a flat list. Because the numbering is fully configurable, you can match almost any style, from a simple one-per-line count to a padded, evenly aligned column of numbers.

Everything happens inside your browser using JavaScript. The tool splits your text on line breaks, assigns numbers according to your chosen start value and step, and joins the result back together. No text is sent over the internet, so your drafts, code and lists remain private on your own device the entire time.

Features

• Adds a sequential number to the start of every line in your pasted or uploaded text.
• Custom start value lets you begin numbering from one, zero or any other integer you choose.
• Custom step lets you increment by two, ten or any interval instead of counting one at a time.
• A configurable separator controls the text placed between each number and its line content.
• Optional zero padding aligns numbers to the same width so the numbered column stays perfectly straight.
• An option skips blank lines so empty rows are preserved without consuming a number in the sequence.
• Runs fully offline in your browser with no sign-up, no upload and no limit on the size of your text.

How to use Add Line Numbers

1. Paste your text or list into the input box, or upload a plain text file to load its contents.
2. Set the start value and step to control where numbering begins and how much it increases each line.
3. Type the separator you want, such as a dot and space or a closing bracket, between number and text.
4. Toggle padding to align all numbers to the same width, and toggle skip-empty to leave blank lines unnumbered.
5. Copy the numbered result with one click or download it as a plain text file for use elsewhere.

Benefits

• Teachers turn a list of questions into a cleanly numbered worksheet without renumbering by hand.
• Code reviewers add line numbers to a snippet so they can reference exact positions in feedback.
• Writers create ordered checklists and step-by-step guides from a plain list in a single action.
• Analysts label rows of data for quick reference during meetings and written summaries.
• Anyone documenting a process gets consistent, aligned numbering that is easy to read and cite.

Padding matters when your list crosses into double or triple digits, because unpadded numbers cause the text after them to shift left and right as the number width grows. Enabling zero or space padding keeps every line aligned to the same column, which is especially helpful for code listings and long reference documents where a ragged left edge is distracting.

The skip-empty option is useful when your text already has intentional blank lines separating sections. Rather than wasting a number on each gap, the tool leaves those lines untouched and continues the count on the next line with content, preserving your structure while still numbering the meaningful rows.