Keigo Companion
A hosted Japanese keigo (敬語) study app that teaches which honorific register applies to whom — uchi/soto, hierarchy, setting — not just verb conjugation. Includes a hand-authored scenario bank, a step-by-step reasoning diagnostic, and a tiered explain-on-miss system where a free rule-based diagnoser handles most mistakes and an LLM only fires as a capped fallback.
Role
Full-Stack Engineer
Timeline
Personal project, ongoing
Impact & Metrics
- Shipped a working judgment-first practice flow: verb drills, scenario practice, decision diagnostic, nuance notes, and progress tracking
- Kept explanations free for the large majority of misses via the rule-based diagnoser, with LLM usage capped as a fallback
- 100% free, no account required, no ads
- Needed a judgment-first teaching approach, not another conjugation drill
- Explanations had to stay free and fast for the common case — an LLM call on every miss wasn't sustainable at zero budget
- Content (scenarios, nuance notes) had to be hand-authored for accuracy rather than model-generated
Tiered explain-on-miss system
Built a rule-based diagnoser as the first line of explanation for wrong answers, with Claude (Haiku 4.5) as a capped fallback only when the rule-based system can't explain the mistake — keeping the app free to run at scale.
Scenario- and decision-first practice modes
Added Scenario Practice and a Decision Diagnostic that walk through the actual social reasoning (who you're speaking to, in/out-group, context) instead of jumping straight to verb forms.
Optional sync without forcing accounts
Used Supabase for auth and cross-device progress sync, but kept the core drills fully usable with no account and no ads.