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

SUBTLEX-CH and CC-CEDICT

The Chinese Most common words decks’ words and bands come from SUBTLEX-CH (Cai, Q., & Brysbaert, M. (2010). SUBTLEX-CH: Chinese word and character frequencies based on film subtitles. PLoS ONE 5(6): e10729), and their definitions and pinyin from CC-CEDICT by MDBG, licensed under CC BY-SA 4.0.

SUBTLEX-CH · CC-CEDICT · CC BY-SA 4.0

Jiten and JMdict

The Japanese Most common words decks’ words and bands come from Jiten’s all-media frequency list (jiten.moe, version 26-10-23), and their definitions and readings from JMdict 3.6.2 by the EDRDG. Licensed under CC BY-SA 4.0.

Jiten · EDRDG licence · 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

Pitch accents and pronunciations

The Japanese words’ pitch accents come from three sources, in this order: Kanjium’s accent list by mifunetoshiro, licensed under CC BY-SA 4.0; UniDic 3.1 by the UniDic Consortium, under the BSD license whose full text is in the app, under Settings → Acknowledgements → Open-source licenses; and English Wiktionary, by the Wiktionary contributors, licensed under CC BY-SA 4.0 and the GNU Free Documentation License. A word none of them lists takes the accent predicted by Open JTalk, from the HTS Working Group. The words’ recordings are synthesized with Google Cloud Text-to-Speech.

UniDic · Kanjium · Wiktionary · Open JTalk · Google Cloud Text-to-Speech · CC BY-SA 4.0 · GNU FDL

FrequencyWords

The German decks’ words, their levels and their order come from Hermit Dave’s FrequencyWords German list, built from OPUS OpenSubtitles 2018 (opensubtitles.org). Licensed under CC BY-SA 4.0.

FrequencyWords · CC BY-SA 4.0

Wiktionary

The German words’ definitions, genders and plurals come from English Wiktionary, by the Wiktionary contributors, through kaikki.org’s wiktextract extract (Tatu Ylonen, LREC 2022). Licensed under CC BY-SA 4.0 and the GNU Free Documentation License.

Wiktionary · kaikki.org · CC BY-SA 4.0 · GNU FDL

SUBTLEX-US, JMdict and CMUdict

The English Most common words decks’ words and bands come from SUBTLEX-US (Brysbaert, M., & New, B. (2009). Moving beyond Kučera and Francis: A critical evaluation of current word frequency norms and the introduction of a new and improved word frequency measure for American English. Behavior Research Methods, 41(4), 977–990). Their Japanese definitions come from JMdict by the EDRDG, licensed under CC BY-SA 4.0, and their pronunciations from the CMU Pronouncing Dictionary, © 1993–2015 Carnegie Mellon University, under the BSD license whose full text is in the app, under Settings → Acknowledgements → Open-source licenses.

SUBTLEX-US · EDRDG licence · CMUdict · CC BY-SA 4.0

FrequencyWords (French), Wiktionary and JMdict

The French decks’ words, their levels and their order come from Hermit Dave’s FrequencyWords French list, built from OPUS OpenSubtitles 2018 (opensubtitles.org), licensed under CC BY-SA 4.0. The French words, their genders, plurals and IPA pronunciations come from English Wiktionary, by the Wiktionary contributors, through kaikki.org’s wiktextract extract (Tatu Ylonen, LREC 2022), licensed under CC BY-SA 4.0 and the GNU Free Documentation License. The most common words’ Japanese and English definitions are Ippo’s own; the rest of the English ones come from English Wiktionary, and the rest of the Japanese ones from JMdict by the EDRDG, licensed under CC BY-SA 4.0.

FrequencyWords · Wiktionary · kaikki.org · EDRDG licence · CC BY-SA 4.0 · GNU FDL

ShareAlike. Ippo adapted this data: it merged the JLPT lists with its lesson decks, chose common spellings, ranked the words by frequency, took the Japanese pitch accents from its sources in order of preference, and for Chinese shortened the CC-CEDICT definitions. For German, it gathered the frequency list’s word forms into dictionary words, gave them their Wiktionary definitions, genders and plurals, and split them into levels. For English, it gathered SUBTLEX-US’s word forms into dictionary words and chose Japanese definitions for them from JMdict’s English glosses. 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.

This website and the web app also serve Noto Sans CJK (© Adobe, SIL Open Font License 1.1) and Roboto (© Google, Apache License 2.0), with their license texts at /app/fonts/LICENSE.txt.

Software

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