Japanese by Renzo is an offline Japanese dictionary application for iOS and Android developed by renzo inc. It provides 174,650+ dictionary entries, 52,000 example sentences, stroke order animations, handwriting recognition, SKIP code lookup, and a built-in spaced repetition flashcard system in a single offline-capable app.
In-Depth Explanation
Platform: iOS and Android (Google Play: `com.renzo.japanese`). 500,000+ downloads on Android; 4.4 stars with over 5,600 ratings. Free with optional in-app purchases. Fully offline; all dictionary and sentence data stored on device. Last updated June 2025.
Japanese by Renzo is built on JMDict dictionary data and the KanjiDic2 kanji database, covering the same core vocabulary as other JMDict-based tools while adding several features that distinguish it from simpler dictionary apps: built-in SRS flashcards, multiple kanji search methods, and comprehensive verb and adjective conjugation tables.
Dictionary and Entry Content
Each word entry includes English definitions, readings, part-of-speech tags, JLPT level, common-usage markers, and example sentences. Kanji entries include stroke order animations, on-yomi, kun-yomi, radical components, and grade-level classification.
Search Methods
Lookup options include: standard text input (kanji, kana, romaji); handwriting recognition (draw an unknown character to identify it); SKIP (System of Kanji Indexing by Patterns) code entry; stroke count; and radical selection. SKIP codes — a character-classification system based on geometric shape — allow lookup of kanji without knowing their reading or radical name.
Built-In SRS Flashcards
Unlike many dictionary apps that rely on external tools for review, Japanese by Renzo includes a built-in spaced repetition flashcard system. Learners can add words from dictionary lookups directly to SRS review decks, keeping the lookup-and-review loop within a single application. Pre-built vocabulary decks are organized by JLPT level (N5–N1).
History
Japanese by Renzo is developed by renzo inc., an independent developer focused on offline-capable Japanese study tools. The app has been available on iOS and Android for several years and reached 500,000 or more downloads on Android. The combination of offline dictionary depth and built-in SRS — rather than routing learners to a separate flashcard tool — has been a consistent design principle.
Common Misconceptions
“SKIP code lookup requires special preparation.”
SKIP codes classify kanji by geometric shape (whether the character divides horizontally, vertically, contains an enclosure, or is solid). Any learner can use SKIP lookup by examining the shape of an unknown character — no prior knowledge of radicals or readings is needed. The system is documented within the app.
“Built-in SRS is less effective than Anki.”
The SRS algorithm in Japanese by Renzo and dedicated systems like Anki both implement spaced repetition review. The practical difference lies in card customization and deck portability, not core review effectiveness; built-in SRS is fully sufficient for learners who prefer not to maintain a separate flashcard application.
Social Media Sentiment
Japanese by Renzo appears regularly on r/LearnJapanese in dictionary recommendation threads. It is typically noted as a strong offline option with comprehensive search methods. The built-in SRS is appreciated by users who want everything in one app. Some users prefer it to Jsho for its additional kanji entry detail (stroke order, SKIP lookup) while others prefer Jsho’s lightweight interface. The SKIP lookup feature is specifically mentioned in threads about looking up kanji in physical books and materials.
Last updated: 2026-05
Related Terms
See Also
Research
- renzo inc. (n.d.). Japanese — Language Study App [Mobile application]. Google Play Store (`com.renzo.japanese`). https://play.google.com/store/apps/details?id=com.renzo.japanese
Summary: Primary source for all app-specific details including developer, feature set (174,650+ entries, 52,000 examples, handwriting recognition, SKIP lookup, stroke order, built-in SRS with JLPT decks), offline capability, and download and rating figures. Verified May 2026.
- Ebbinghaus, H. (1885). Über das Gedächtnis: Untersuchungen zur experimentellen Psychologie. Duncker & Humblot.
Summary: Established the forgetting curve — the empirical observation that memory fades predictably without review — providing the theoretical foundation for the spaced repetition flashcard system built into Japanese by Renzo.
- Cepeda, N. J., Pashler, H., Vul, E., Wixted, J. T., & Rohrer, D. (2006). Distributed practice in verbal recall tasks: A review and quantitative synthesis. Psychological Bulletin, 132(3), 354–380.
Summary: Empirical meta-analysis confirming that distributing review across spaced intervals produces substantially better long-term retention than massed practice, providing scientific support for the SRS scheduling mechanism in Japanese by Renzo’s built-in flashcard system.