Add Line Numbers Online

It's common to find yourself sharing code snippets in Slack or pasting server logs into emails where my IDE's line numbers disappear. Trying to say "look at the 14th line from the top" is a nightmare. That's exactly why This tool tool—to instantly prefix every line of your text with sequential numbering.

What does it do?

This utility takes your raw text or code and automatically injects sequential numbers at the start of every line. It's incredibly useful for code reviews outside of GitHub, debugging log files, or formatting legal documents where absolute referencing is necessary.

How This tool is designed It

I wanted this to be as frictionless as possible. When you paste your text, the script immediately splits it by newline characters and loops through, appending the current index. Because this all happens locally in your browser (client-side), it's instantaneous and 100% private. Even if you're pasting sensitive API logs, your data never touches a server.

Features You'll Actually Use

• Zero-Padding: If you're dealing with hundreds of lines, standard numbering gets messy (9 vs 10). I added a zero-padding toggle so numbers align perfectly (09, 10).
• Ignore Blank Lines: Sometimes you don't want empty spaces throwing off your count. You can configure it to skip empty lines completely.
• Custom Separators: By default it uses 1. , but you can change it to 1: or 1 | depending on your formatting needs.

Quick Guide

1. Paste your raw text into the left pane.
2. Adjust your starting number and separator preference.
3. Hit copy and you're done. No signups, no ads blocking the button.