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Credits and licenses

All course content is either written for this site or comes from openly licensed sources, listed below for each course. Example sentences credit their Tatoeba authors on every page where they appear.

The site code is MIT licensed. Grammar lessons written for the site, and word data derived from CC BY-SA sources (CC-CEDICT, Wiktionary), are shared under CC BY-SA 4.0.

Updated October 21, 2026

Mandarin Chinese

• ivankra/hsk30 (HSK 3.0 word list): HSK 3.0 levels 1 and 2 (2021 standard) with pinyin and part of speech. License: MIT.
• CC-CEDICT: English definitions and numbered pinyin. Derived data is shared under CC BY-SA 4.0. License: CC BY-SA 4.0.
• Tatoeba: Example sentences and translations. Each sentence credits its author. License: CC BY 2.0 FR.
• Hanzi Writer + hanzi-writer-data (Make Me a Hanzi): Stroke order animation and writing quizzes. License: MIT (code), Arphic Public License (stroke data).
• Original grammar lessons: Grammar explanations and their example sentences are written for this site. License: CC BY-SA 4.0.

Spanish

• FrequencyWords (hermitdave), OpenSubtitles 2018: Word frequency ranks used to order the core vocabulary. License: CC BY-SA 4.0 (lists), MIT (code).
• Wiktionary via kaikki.org: Short English glosses, gender and IPA. Derived data is shared under CC BY-SA 4.0. License: CC BY-SA 4.0.
• Tatoeba: Example sentences and translations. Each sentence credits its author. License: CC BY 2.0 FR.
• Original grammar lessons: Grammar explanations and their example sentences are written for this site. License: CC BY-SA 4.0.

English

• FrequencyWords (hermitdave), OpenSubtitles 2018: Word frequency ranks used to order the core vocabulary. License: CC BY-SA 4.0 (lists), MIT (code).
• Wiktionary via kaikki.org: Short English glosses, gender and IPA. Derived data is shared under CC BY-SA 4.0. License: CC BY-SA 4.0.
• CC-CEDICT: English definitions and numbered pinyin. Derived data is shared under CC BY-SA 4.0. License: CC BY-SA 4.0.
• ivankra/hsk30 (HSK 3.0 word list): HSK 3.0 levels 1 and 2 (2021 standard) with pinyin and part of speech. License: MIT.
• Tatoeba: Example sentences and translations. Each sentence credits its author. License: CC BY 2.0 FR.
• Original grammar lessons: Grammar explanations and their example sentences are written for this site. License: CC BY-SA 4.0.

French

• FrequencyWords (hermitdave), OpenSubtitles 2018: Word frequency ranks used to order the core vocabulary. License: CC BY-SA 4.0 (lists), MIT (code).
• Wiktionary via kaikki.org: Short English glosses, gender and IPA. Derived data is shared under CC BY-SA 4.0. License: CC BY-SA 4.0.
• Tatoeba: Example sentences and translations. Each sentence credits its author. License: CC BY 2.0 FR.
• Original grammar lessons: Grammar explanations and their example sentences are written for this site. License: CC BY-SA 4.0.

Italian

• FrequencyWords (hermitdave), OpenSubtitles 2018: Word frequency ranks used to order the core vocabulary. License: CC BY-SA 4.0 (lists), MIT (code).
• Wiktionary via kaikki.org: Short English glosses, gender and IPA. Derived data is shared under CC BY-SA 4.0. License: CC BY-SA 4.0.
• Tatoeba: Example sentences and translations. Each sentence credits its author. License: CC BY 2.0 FR.
• Original grammar lessons: Grammar explanations and their example sentences are written for this site. License: CC BY-SA 4.0.

Portuguese

• FrequencyWords (hermitdave), OpenSubtitles 2018: Word frequency ranks used to order the core vocabulary. License: CC BY-SA 4.0 (lists), MIT (code).
• Wiktionary via kaikki.org: Short English glosses, gender and IPA. Derived data is shared under CC BY-SA 4.0. License: CC BY-SA 4.0.
• Tatoeba: Example sentences and translations. Each sentence credits its author. License: CC BY 2.0 FR.
• Original grammar lessons: Grammar explanations and their example sentences are written for this site. License: CC BY-SA 4.0.

German

• FrequencyWords (hermitdave), OpenSubtitles 2018: Word frequency ranks used to order the core vocabulary. License: CC BY-SA 4.0 (lists), MIT (code).
• Wiktionary via kaikki.org: Short English glosses, gender and IPA. Derived data is shared under CC BY-SA 4.0. License: CC BY-SA 4.0.
• Tatoeba: Example sentences and translations. Each sentence credits its author. License: CC BY 2.0 FR.
• Original grammar lessons: Grammar explanations and their example sentences are written for this site. License: CC BY-SA 4.0.

Software

• ts-fsrs (MIT) for spaced review scheduling.
• Hanzi Writer (MIT) with stroke data from Make Me a Hanzi (Arphic Public License).
• Engine ideas from Mathua (MIT).
• Eleventy (MIT) builds the site.