Sensei

Preparing a trip to Japan means learning the basics of Japanese, but the existing offer is scattered: subscription apps, mostly English content, constant internet dependency, often flat learning experience. The goal was to build a single, comprehensive, French-speaking tool able to survive a trip without internet and keep all data on the user's device.

Major language apps run on subscriptions, require constant internet, send data to their servers and impose their own pace. Static course files offer neither interactivity nor progress tracking. No product combined both worlds in French, for a goal as concrete as travelling to Japan independently.

A single HTML file embeds everything: code, data, learning content, audio synthesised via the Web Speech API, handwriting via Canvas, stroke order animated in SVG. A single engine drives 25+ exercise types from the same structured data. A service worker caches everything on first load, and all progress stays in the user's browser. No framework, no external library, not a single network call after install.

A web application installable as a true app on mobile, fully functional offline after the first load. It covers the three Japanese alphabets (137 characters), a survival vocabulary (370+ words), 53 travel kanji, 25 grammar sheets and around twenty verbs conjugated across six forms. The spaced repetition engine automatically prioritises what needs reviewing, and gamification (XP, levels, daily quests, streaks) keeps motivation alive until departure. No ads, no subscription, no data sent outside.