Number Lines
Number Lines normalizes CRLF to LF and formats every line as index+1 followed by '. ' and original content. Blank lines are numbered too. Numbering always starts at 1, uses no padding, and provides no start, step, delimiter, blank-skip, width, alignment, or preservation of existing numbers.
Runs locally — files stay on your deviceAre blank lines numbered?
Yes.
Line numbering is a positional transformation
Every split line receives its current array index, regardless of whether it contains visible text.
How it works
map formats `${i+1}. ${line}` and LF rejoins.
Key concepts
One-based
First line is 1.
Fixed style
No zero padding or alternate marker.
When to use it
- Create a quick review list.
- Add references to plain-text lines.
- Number every record including blanks deliberately.
When not to use it
- Do not expect existing numbers detected.
- Do not expect code-editor-style noncontent numbering.
- Do not use when blank lines should remain unnumbered.
Worked examples
Two
- Input
a\nb- Expected output
1. a\n2. b
Sequential.
Blank
- Input
a\n\nb- Expected output
1. a\n2. \n3. b
Blank counted.
Existing
- Input
5. item- Expected output
1. 5. item
Old number remains.
Common mistakes
Double numbering
Existing prefixes are untouched. Correction: Remove numbers first.
Skipping blanks assumption
They consume sequence values. Correction: Remove empty lines first.
Expecting configurable format
Style is fixed. Correction: Use a template-capable tool.
Best practices
- Clean existing numbering first.
- Decide how blanks should behave.
- Keep source for later renumbering.
Related operations and differences
Add Prefix to Every Line
Choose Add Prefix to Every Line when you need to add the same prefix before every line.; use Number Lines specifically for number lines.
Add Suffix to Every Line
Choose Add Suffix to Every Line when you need to add the same suffix after every line.; use Number Lines specifically for number lines.
Capitalize Every Word
Choose Capitalize Every Word when you need to capitalize the first character of every word.; use Number Lines specifically for number lines.
Extract Email Addresses
Choose Extract Email Addresses when you need to find unique email addresses in text.; use Number Lines specifically for number lines.
Extract URLs
Choose Extract URLs when you need to find unique HTTP and HTTPS links in text.; use Number Lines specifically for number lines.
Line Counter
Choose Line Counter when you need to count the number of text lines.; use Number Lines specifically for number lines.
Limitations and privacy
- Fixed one-based `${n}. ` on every line; no start/step/padding/style, blank skip, existing-number detection, selection, or CRLF preservation.
Text is transformed locally in this browser and is not uploaded by the tool.
Frequently asked questions
Where does numbering start?
At 1.
Are blanks numbered?
Yes.
Can I use 001?
No.
Are old numbers removed?
No.