Sottaku is a free language learning application for iOS and Android, developed by Sottaku Inc., supporting Japanese, Chinese, Korean, and English. The app combines FSRS-based spaced repetition flashcards, grammar guides, a Japanese dictionary with furigana and audio, community chat, and a companion browser extension.
Platform: https://sottaku.app — iOS (App Store ID 6756599573) and Android (com.sottakumobile); browser extension available separately.
In-Depth Explanation
Sottaku’s Japanese dictionary provides definitions with furigana readings and audio pronunciation. The SRS flashcard system uses FSRS (Free Spaced Repetition Scheduler), an algorithm developed to improve scheduling accuracy over older algorithms such as SM-2 by modeling memory more precisely. Users can study from pre-made decks or build custom lists, with the SRS handling review timing. Additional quiz and challenge modes provide variety in review beyond standard flashcard format.
Community features include a language exchange and discussion chat within the app and a leaderboard system, adding a social accountability layer to individual study. Cross-device sync is supported.
The Sottaku-Yomitan browser extension integrates with the web-browser environment to show pop-up definitions on Japanese text — similar in concept to the widely used Yomitan (formerly Yomichan) dictionary extension. The Sottaku extension uses the app’s own dictionary data.
Sottaku launched in 2025. As of early 2026, the iOS version had a perfect 5.0 rating across ten reviews, and the Android version maintained a 4.9 rating on Google Play.
Social Media Sentiment
Sottaku is a recent entrant in the Japanese learning app space (2025 launch) and community discussion as of early 2026 is limited but positive in tone. The app’s use of FSRS has drawn favorable comparisons from learners familiar with the algorithm’s advantages over older SRS implementations. The availability of the browser extension has been noted as a differentiating feature for immersion learners who use web-based Japanese content. No significant critical discussion was observed across major Japanese-learning communities as of early 2026.
Last updated: 2026-05
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Research
- Sottaku Inc. (n.d.). Sottaku — Language Learning [Mobile application]. App Store (ID 6756599573) and Google Play (com.sottakumobile). https://sottaku.app
Summary: Primary source for all app-specific details in this entry, including developer (Sottaku Inc.), supported languages (Japanese, Chinese, Korean, English), FSRS-based SRS, browser extension (Sottaku-Yomitan), community features, and pricing (free + Pro tier). Verified May 2026.
- Ebbinghaus, H. (1885). Über das Gedächtnis: Untersuchungen zur experimentellen Psychologie. Duncker & Humblot.
Summary: Established the forgetting curve — the theoretical foundation for all spaced repetition algorithms including FSRS. Demonstrated that memory decays predictably over time without review, requiring strategically spaced review sessions to maintain retention.
- Wozniak, P. A., & Gorzelańczyk, E. J. (1994). Optimization of repetition spacing in the practice of learning. Acta Neurobiologiae Experimentalis, 54, 59–62.
Summary: Empirical study establishing the mathematical basis for optimizing repetition intervals in spaced learning systems; part of the foundational research lineage that informed the development of modern SRS algorithms, including FSRS as used by Sottaku.