About Katakana Converter

A free, open-source tool for converting English text to Japanese Katakana — built entirely in the browser.

Our Mission

Katakana Converter was created to provide a fast, accurate, and completely free way to convert English words into Japanese Katakana characters. Unlike other tools that rely on external APIs or machine learning services, our converter runs entirely in your browser using pure JavaScript.

We believe language tools should be accessible to everyone — no accounts, no subscriptions, no data collection. Your text never leaves your device.

How It Works

Our conversion engine uses a sophisticated multi-stage pipeline:

  1. Normalization — Input text is cleaned, lowercased, and tokenized into individual words.
  2. Grapheme-to-Phoneme (G2P) — Each word is processed through 100+ ordered rules that analyze English spelling patterns to extract phonemes (speech sounds) using an ARPAbet-style notation system.
  3. Phoneme-to-Katakana Mapping — Phonemes are mapped to Japanese Katakana syllables using a comprehensive consonant-vowel table, with proper handling of long vowels (ー), geminate consonants (ッ), and moraic nasals (ン).
  4. Post-Processing — The output is polished by normalizing long vowels, removing invalid combinations, and ensuring only valid Katakana characters remain.

For common English loanwords with irregular pronunciations, we also maintain a curated dictionary of 200+ words to ensure the most accurate standard Katakana representations.

Technology

Katakana Converter is built with:

  • Zero external dependencies — Pure vanilla JavaScript, HTML, and CSS
  • No API calls — Everything runs client-side in your browser
  • No build tools required — Just open the HTML file and start converting
  • Multiple converter workflows — Name conversion, full-width formatting, kana swapping, and kanji reading support from one browser-based toolset

About Katakana

Katakana (カタカナ) is one of three Japanese writing systems, alongside Hiragana and Kanji. It is primarily used for:

  • Foreign loanwords (gairaigo) — e.g., コーヒー (coffee), コンピュータ (computer)
  • Technical and scientific terms
  • Onomatopoeia (sound words)
  • Emphasis (similar to italics in English)
  • Names of plants, animals, and foreign names

The Katakana writing system consists of 46 basic characters, each representing a syllable (mora) in the Japanese language. When English words are borrowed into Japanese, they are adapted to fit the Japanese phonological system — for example, consonant clusters are broken up with epenthetic vowels, and sounds not present in Japanese (like "l" and "th") are approximated with the closest Japanese equivalents.

Contact

Have questions or suggestions? Visit our Contact page to get in touch.