Does this add the prefix to every line, or every word?

It adds the prefix to every word, splitting on whitespace, not by line. Use Line Prefix Adder instead if you want each line, rather than each word, prefixed.

Is the original spacing preserved?

Yes, the tool splits on runs of whitespace while keeping them as separate pieces, so the exact spaces, tabs, or newlines between words are reproduced in the output.

Word Prefix Adder Online - Prepend Text to Every Word

Overview

Introduction

Turning a list of keywords into hashtags, or marking every word in a sentence with a shared symbol, means prefixing each word individually while leaving the spacing between them untouched.

It runs entirely client-side, so nothing you paste is ever uploaded to a server.

What Is Word Prefix Adder?

A word-based prefixing tool that prepends your chosen prefix to the start of every word in the input, while leaving the original whitespace between words exactly as it was.

It runs entirely client-side as part of this site's String Tools collection, so nothing you paste is ever uploaded to a server.

How Word Prefix Adder Works

The tool splits the input on runs of whitespace using a capturing regular expression, so the whitespace pieces are kept in the resulting array, then prepends the prefix to every non-whitespace piece and rejoins everything.

The transformation happens synchronously in JavaScript the moment you type, with no network round trip involved.

When To Use Word Prefix Adder

Use it to turn a list of keywords into hashtags, mark every token in a sentence with a shared symbol, or prefix each word for a custom markup format.

It's a fast way to get the answer without opening a code editor, a REPL, or writing a one-off script just to check.

Often used alongside Word Suffix Adder, Line Prefix Adder and Prefix Adder.

Features

Advantages

Preserves the exact original whitespace between words, including multiple spaces or tabs.
Works on any whitespace-separated text, not just single-spaced sentences.

Limitations

Splits purely on whitespace, so punctuation attached to a word (like a trailing comma) is treated as part of that word.

Examples

Generating hashtags from keywords

Input

alpha beta gamma

Output

#alpha #beta #gamma

With prefix '#', each of the three space-separated words gets the symbol prepended, and the single spaces between them are preserved.

Best Practices & Notes

Best Practices

Remember that punctuation attached to a word is treated as part of it, so 'word,' becomes '#word,' rather than '#word,'.

Developer Notes

The implementation uses `input.split(/(\s+)/)` with a capturing group so whitespace runs are kept as separate array entries, then maps only the non-whitespace entries with `prefix + part` before rejoining with `join("")`.

Word Prefix Adder Use Cases

Generating hashtags from a list of keywords
Prefixing every word in a sentence for a custom markup or DSL
Marking each token in a tag list with a shared symbol

Common Mistakes

Expecting the prefix to apply per line rather than per word; use Line Prefix Adder for line-based prefixing instead.

Tips

Use Word Suffix Adder alongside this tool to wrap every word with both a prefix and a suffix.

Word Prefix Adder