Can I start counting from a number other than 1?

Yes. Set the "Start at" field to any whole number (including 0 or a negative number) and the lines are numbered sequentially from there.

How accurate is the zero padding?

Padding width is computed from the largest number that will actually be emitted, so every number lines up to the same width with no off-by-one errors.

Is my text uploaded anywhere?

No — all numbering happens locally in your browser and nothing is sent to a server.

Add Line Numbers

Prefix every line with a sequential number.

Add line numbers to text

Prefix every line of your text with a sequential number. Pick the start value, the separator (dot, colon, pipe, tab or space), turn on zero padding so the numbers align, and optionally skip blank lines so only content lines are numbered.

Everything runs in your browser — nothing is uploaded.