Adding line numbers to text usually means doing it in an editor or with a script. The Number Text Lines tool does it in the browser: paste your text, and each line gets a prefix like 1., 2., 3.—no sign-up and no data sent to a server.
What does Number Text Lines do?
Number Text Lines is a free online tool that adds a line number prefix to each line (e.g. 1., 2., 3.). You can set the format and the starting number. It is used for code snippets, error logs, reference lists, or any place you need to refer to lines by number. All processing runs in your browser; there is no upload, no storage, and no account required.
Key Features
- Line number prefix — Each line gets a number prefix. Formats like 1., 1), (1), or custom are supported. You can set the starting number.
- Custom format and start — Use formats like 1., 1), (1), or custom. Set the starting number (e.g. 1 or 10).
- Any input — Paste or type any text; each line gets a number. Empty lines are also numbered unless you remove them first.
- Instant result — Paste, set format and start, and see the numbered result. Copy when ready.
- Privacy-first — All processing happens in your browser. Your text is never sent to any server.
- No account — Use as often as you need without sign-up.
How to Use Number Text Lines
- Open the Number Text Lines tool.
- Paste or type your text (multi-line).
- Choose the number format (e.g. 1., 1), (1)) and the starting number (e.g. 1). View the numbered result. Copy the result.
- Paste into your doc, readme, or support reply. Use the "Use tool" button on the docs page if you are reading this from the documentation.
Real Use Cases
- Code snippets — Add line numbers so you can refer to "line 5" or "lines 10–12" in docs or support.
- Error logs — Number log lines for reference when reporting or debugging.
- Reference lists — Number a list so people can cite by line (e.g. "item 3").
- Excerpts and quotes — Number lines of a pasted excerpt for discussion or review.
- Teaching and feedback — Number lines so feedback can reference specific lines.
- Paste from middle of file — Set the start number to match the source file (e.g. start at 50 if you copied from line 50).
Why Use Number Text Lines Instead of Alternatives?
- vs. Editor line numbers — Editor line numbers are for display only; they are not part of the text. This tool adds numbers as text so they appear in paste, email, or docs.
- vs. Manual numbering — No need to type 1., 2., 3. by hand. Paste, set format, copy.
- vs. Scripts — No coding. Works in any browser.
- vs. Prefix/suffix tools — Prefix Text Lines adds a fixed string; this tool adds incrementing numbers. Use number format and start for full control.
The tool numbers from the start of the pasted text. If you copied from the middle of a file, set the start number to match your source.
Benefits for Developers, Support, and Educators
- Developers — Number code or log excerpts for docs or bug reports. No one-off script.
- Support — Number error output or config so users can reference "line 7."
- Educators — Number passages for reference in feedback or discussion.
Common Mistakes
- Line numbers do not match my editor — The tool numbers from the start of the pasted text. If you copied from the middle of a file, set the start number to match your source.
- Empty lines numbered — Empty lines get a number too. Remove empty lines first with Delete Empty Lines if you want only content lines numbered.
- Wrong format — Choose the format (1., 1), (1)) that matches your style. Custom format may be available depending on the tool.
- Forgetting to copy — The result is not saved. Copy before closing the tab or refreshing.
Frequently Asked Questions
What does number text lines do?
It adds a line number prefix to each line (e.g. 1., 2., 3.). You can set the format and the starting number.
Can I change the number format?
Yes. You can use formats like 1., 1), (1), or custom. You can also set the starting number.
What input does it accept?
Paste or type any text; each line gets a number. Empty lines are also numbered unless you remove them first.
Is my text stored?
No. All processing happens in your browser. Your text is never sent to any server.
When should I use line numbers?
Use it for code snippets, error logs, reference lists, or any place you need to refer to lines by number.
Why do line numbers not match my editor?
The tool numbers from the start of the pasted text. If you copied from the middle of a file, set the start number to match your source.
Conclusion and Try the Tool
Number Text Lines gives you numbered lines in seconds: paste, set format and start, copy. No account, no server round-trip. For a fixed prefix use Prefix Text Lines, for suffix use Suffix Text Lines, and for word counts use the Word Counter.
Use the Number Text Lines tool to add line numbers.