Add Line Numbers
Prefix every line with a counter: custom start, step, and separator.
Browser onlyYour data never leaves this device.
Runs entirely in your browser. Your text never leaves this device and is never stored.
Details: Privacy policy
Input
Options apply live. Nothing is stored.
First number in the sequence.
Added to the previous number.
Printed between the number and the line.
Off skips empty lines when counting.
Result
No text yet.
Paste lines above to number them.
Add Line Numbers prefixes every line of your text with a counter, using a start value, a step and a separator you choose, so a long file becomes something a colleague can cite by row. It is the small utility you reach for when a log, a dataset or a shared document has to be discussed line by line: number it once, paste it into the thread, and everyone is looking at the same reference. Numbers are plain and unpadded rather than aligned into columns, and a negative start keeps its minus sign, because inventing a format is not this page's job. Blank lines can be numbered or skipped, which matters when the paste contains paragraph breaks that are not really rows. The limits are stated before you paste: at most a hundred thousand lines and a million characters per run, and a projected output above two megabytes is refused before anything is allocated, so an accidental paste of a huge file fails loudly rather than freezing the tab. Nothing is uploaded and nothing is stored.
Key facts
- Input
- Multi-line text
- Output
- Text with a counter prefix on each line
- Limits
- At most 100,000 lines and 1,000,000 characters per run; larger pastes are rejected before processing. Projected output above 2 MB is rejected before allocation.
- Processing
- In your browser — nothing is uploaded
- Sign-up
- Not required
- Cost
- Free
Limits above are read from the same code that enforces them; formats are the ones the tool accepts and produces.
How to use Add Line Numbers
- Paste text and set start, step, and separator.
- Choose whether blank lines are numbered and which line ending to emit.
- Copy the numbered text or clear to start over.
What you get
- The text with a counter prefixed to every line, using your start value, step and separator.
- Plain unpadded numbers, so a negative start keeps its minus sign instead of being padded.
- A rejection before processing when a paste exceeds 100,000 lines, 1,000,000 characters or 2 MB of projected output.
When to use Add Line Numbers
- Number log lines from a custom start so a teammate can cite exact rows.
- Prefix dataset rows with stepped counters before importing them elsewhere.
- Number the lines of a shared document so a reviewer can point at row 214 instead of quoting it.
Frequently asked questions about Add Line Numbers
Does Add Line Numbers upload my text?
No. All numbering runs locally in your browser; nothing is sent, stored, or logged.
Can numbering start below zero?
Yes. Start accepts whole numbers from -1,000,000 to 1,000,000, and negative counters keep their minus sign without padding.
What happens to blank lines?
Your choice: number them like any other line, or pass them through untouched while the counter skips ahead only on numbered lines.
Why was my large input rejected?
Inputs above 100,000 lines, or outputs projected above 2 MB, are refused before allocating memory. Split the input or shorten the separator.
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