Acknowledgements

Ippo is built on open word data and open fonts. Thank you to everyone who made them.

Word data

OpenJLPT

The JLPT N5–N1 decks come from OpenJLPT v0.3.0, which uses JMdict and KANJIDIC2 from the Electronic Dictionary Research and Development Group (EDRDG), Jonathan Waller’s JLPT lists and Tatoeba. Licensed under CC BY-SA 4.0.

OpenJLPT · EDRDG licence · Jonathan Waller’s JLPT lists · Tatoeba · CC BY-SA 4.0

wordfreq

Japanese and Chinese new cards are ordered by word frequency ranks derived from wordfreq 3.1.1 by Robyn Speer, whose data includes Wikipedia, OPUS OpenSubtitles 2018 (opensubtitles.org), SUBTLEX, NewsCrawl, GlobalVoices, Google Books Ngrams, OSCAR, Twitter, Reddit and, for Chinese, the Jieba word list. Chinese frequencies include SUBTLEX-CH (Cai, Q., & Brysbaert, M. (2010). SUBTLEX-CH: Chinese word and character frequencies based on film subtitles. PLoS ONE 5(6): e10729), which is freely available data. The ranks are licensed under CC BY-SA 4.0.

wordfreq · Citation · SUBTLEX-CH · CC BY-SA 4.0

JMdict usually-kana list

The words Ippo writes in kana, such as めがね and たいてい, are marked from JMdict by the EDRDG, through jmdict-simplified. Licensed under CC BY-SA 4.0.

EDRDG licence · jmdict-simplified · CC BY-SA 4.0

ShareAlike. Ippo adapted this data: it merged the JLPT lists with its lesson decks, chose common spellings and ranked the words by frequency. The word data Ippo derives from these sources is shared under the same license, CC BY-SA 4.0.

Fonts

The app uses these fonts under the SIL Open Font License 1.1. The full license texts are in the app, under Settings → Acknowledgements → Open-source licenses.

Software

Ippo is made with Flutter and other open-source packages. Their licenses are in the app, under Settings → Acknowledgements → Open-source licenses.