Credits and licenses

Updated November 14, 2026.

EnglishLock exists thanks to the work of other people and of open projects. Thank you.

Words and levels

CEFR-J Wordlist (version 1.6), by Yukio Tono, Tokyo University of Foreign Studies. Levels A1 to B2. Commercial use allowed with credit to the source.
Octanove Vocabulary Profile C1/C2 (1.0), by Octanove Labs, an extension of CEFR-J. License CC BY-SA 4.0.
wordfreq, by Robyn Speer, used to sort the words by frequency. License CC BY-SA 4.0.

The sentences, translations, written pronunciations (IPA) and tips were written by the EnglishLock team.

The pronunciation is recorded with the Azure neural voice (Microsoft). Where there is no recording, the app uses the phone's own voice.

The scheduling of reviews uses the open-source FSRS algorithm, through the ts-fsrs library.

React, Capacitor, RevenueCat Purchases SDK and Rive (mascot animation), each under the license of its authors, available on their websites.

Bricolage Grotesque, by Mathieu Triay, SIL Open Font License 1.1.

Apple, App Store, Google Play, Instagram, TikTok and YouTube are trademarks of their owners and are not affiliated with EnglishLock.