● in progress2026
動詞活用トレーナー — Japanese verb trainer
Drill Japanese verb conjugation with Anki-style spaced repetition — romaji→kana input, 13 forms, JLPT filter and example sentences with automatic furigana after every answer.
- role
- Solo developer
- stack
- JavaScript · HTML · CSS · WanaKana · kuromoji.js · GitHub Pages
Problem
Textbooks give you conjugation tables, but at N3/N2 you need to be fast: see 通う + たら形 and type かよったら without thinking. Flashcard apps can't check conjugations, they only compare strings someone typed in beforehand.
Solution
- A rule-based conjugation engine handles godan, ichidan, irregular and する verbs for 13 forms. New verbs only need dictionary data, and every form is generated.
- Romaji → hiragana while typing, like an IME (
taberu → たべる,nn → ん). - SM-2 spaced repetition with the four Anki ratings (keys 1–4). Two modes: dictionary form → conjugation, or meaning → verb.
- After every answer: an explanation and four example sentences (2 basic, 2 advanced) with translations and automatic furigana (kuromoji tokenizer).
- Plain HTML/CSS/JS with no build step. Progress stays in
localStorage.
Lessons learned
- Japanese conjugation is very regular once you model the verb class and the last kana. The engine is a small table of rules, not a list of exceptions.
- Rendering user-facing text safely matters even in a hobby app: one refactor fixed an XSS hole in the example renderer.