Tools / add-prefix-to-lines

Add a prefix to each line

Prepend any string to every line — Markdown bullets, quote characters, indents, log tags. Pick a preset or type your own.

PREFIX
OPTIONS
INPUT · LINES · CHARS
OUTPUT · LINES · CHARS

            
DONE · ran in 0.00ms ·
§01 — ABOUT THIS TOOL

For when every line needs the same thing in front.

Turning a paste into a Markdown bullet list, quoting an email reply, indenting a code paste, prefixing log lines with a timestamp — they're all the same operation: put this text at the start of every line.

Type any prefix in the box. Blank lines are skipped by default so you don't end up with rows that are nothing but the prefix.

§02 — HOW TO USE 03 STEPS
STEP 01 01 / 03

Paste your lines

Drop in one item per line.

STEP 02 02 / 03

Type your prefix

Anything. "- " for bullets, "> " for quotes, " " for indent, " • " for a fancier bullet.

STEP 03 03 / 03

Copy the result

Hit Copy. The output preserves your original line order and structure.

§03 — QUESTIONS 6 ANSWERS
01

Are blank lines prefixed?

Not by default — they stay blank. Turn off SKIP BLANKS to prefix them too.

Yes. Type a literal tab, or use \t — the input is treated literally.

It's added again. We may add an idempotent "Strip prefix" mode later — for now just don't re-run on already-prefixed lines.

It's not — but for a one-shot paste, a tool is faster than firing up an editor.

Not directly — the prefix is the same literal string on every line. For numbered lists, paste into a Markdown editor and start each line with 1. (Markdown auto-numbers the rest), or use a quick spreadsheet trick: paste into column B, type ="A"&ROW()&". " in A1, fill down, then concatenate. We may add a "Number each line" mode if enough people ask.

Prefix is a linear pass — comfortable up to ~500k lines / 50 MB. Beyond ~5M lines you'll feel a short pause, mostly from allocating the new strings. The preview caps at 5,000 lines with a notice when the result is big, but Copy and Download always return the full result.

§04 — THE OTHER SEVEN 7 / 07
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