Numbering code, scripts and lists
Line numbers make it easier to reference specific lines when discussing code snippets, scripts or long lists — zero-padding keeps numbers aligned for lists with more than 9 items.
Add Line Numbers
Paste your text to add a sequential number in front of every line, with a custom starting number and separator.
How it works
- 1
Paste your input into the editor.
- 2
Choose format / mode options if available.
- 3
Copy the transformed output (it usually updates as you edit).
Why use this tool
- Runs entirely in your browser — nothing is uploaded to a server.
- 100% free, no sign-up, no limits.
- Works in any modern browser — no app install, no extension, no account.
How to use Add Line Numbers
Paste into Add Line Numbers, tweak options, and copy the output. Formatting and conversion run in the browser for this tool.
Tips for better results
Keep a backup of original input before bulk transforms. Invalid input should show an error instead of silent corruption.
Privacy and offline-friendly processing
Whenever possible, Add Line Numbers processes your data locally with JavaScript in this page. That means drafts, secrets, and unfinished work stay on your device by default. Prefer this workflow when you do not want to upload sensitive text, tokens, passwords, or files to a third-party service.
Frequently asked questions
Can I start numbering from a value other than 1?
Yes, set any starting number in the "start" field, including 0 or negative numbers.
What does zero-padding do?
It adds leading zeros so all numbers have the same width — e.g. 01, 02, … 10 instead of 1, 2, … 10.
Is my data uploaded when I use this tool?
For most FlyUtils tools, no. Processing happens in your browser with JavaScript. If a tool ever needs a server, that will be stated clearly on the page.
Is Add Line Numbers free to use?
Yes. Add Line Numbers is free, with no sign-up and no artificial usage caps for normal personal and work use.
Does Add Line Numbers work on mobile?
Yes. The page is mobile-first, so you can paste input, tweak options, and copy results from a phone or tablet.