Line Number Tool
Add or remove line numbers from any text. Configure format, start number, padding, and separator.
Last reviewed: April 2026New to this tool? Click here for instructions
How to Use the Line Number Tool
To use the Line Number Tool, follow these steps:
1. Paste your text into the input area on the left (or top on mobile).
2. Choose a mode - "Add Numbers" to prepend line numbers, or "Remove Numbers" to strip existing ones.
3. Configure the format - choose between N: , N. , N) , or plain N separators.
4. Set the start number - default is 1, but you can start from any integer, including 0.
5. Choose padding - none, space-aligned, or zero-padded for fixed-width columns.
6. Copy or download - click Copy to copy to clipboard or Download to save as a .txt file.
When to Use the Tool in Real Workflows
The Line Number Tool is ideal for scenarios where you need to add or remove line numbers from text. This includes:
1. Code sharing - adding line numbers to a snippet before pasting it into a chat or document so colleagues can reference specific lines precisely.
2. Log file analysis - numbering log lines to track which entries you have reviewed.
3. Document editing - numbering paragraphs or clauses in legal documents, contracts, or specifications.
4. Diff preparation - stripping line numbers from a numbered copy before feeding it to a diff tool.
5. Data processing - adding row numbers to CSV-like plain text when your spreadsheet tool strips them.
6. Teaching - adding line numbers to student code excerpts to annotate feedback by line.
How It Works
The Line Number Tool operates entirely in your browser, ensuring your text remains private and secure. Here's how it works:
1. You input your text into the designated area.
2. You select whether you want to add or remove line numbers.
3. You choose the desired format for the line numbers.
4. You set the starting number and padding options.
5. The tool processes your text and displays the result immediately.
6. You can copy or download the processed text as needed.
Tips, Edge Cases, or Limitations
Here are some tips and considerations when using the Line Number Tool:
1. Privacy: All processing happens locally in your browser, so your text never leaves your device.
2. Formats: The tool supports four formats (N:, N., N), and plain N) to suit different conventions.
3. Padding: Choose padding options to ensure alignment in monospace environments.
4. Removing Numbers: The tool recognizes common line number formats and can strip them effectively.
5. Edge Cases: The tool may not handle extremely long texts or very complex formatting. Always check the output for accuracy.
Frequently Asked Questions
Quick reference
| Parameter | Description | Common Values | Example |
|---|---|---|---|
| start_line | Specifies the starting line number for the tool's operation | 1-1000 | 10 |
| end_line | Defines the ending line number for the tool's operation | 1-1000 | 50 |
| comparison_operator | Operator to compare line numbers (>, <, >=, <=) | > < >= <= | >= 100 |
| line_count | Total number of lines to process | 100-1000 | 200 |
| exclude_lines | Range of lines to exclude (format: start-end) | 5-20 | 5-20 |
| include_pattern | Regex pattern to match line content | ^[0-9]+$ | ^[0-9]+$ |
Example walk-through
Worked example: step-by-step
Step 1. Navigate to the Line Number Tool webpage and locate the text input area.
Step 2. Paste the following sample text into the input box:
Hello, world!
This is a test.
Line numbers are fun.
Step 3. Click the "Add Line Numbers" button to process the text.
Step 4. View the transformed output with line numbers added:
1. Hello, world!
2. This is a test.
3. Line numbers are fun.
Step 5. Copy the formatted text for further use. The tool automatically preserves original formatting while adding sequential line numbers.