AI-powered vocabulary learning from real English articles.
Paste any article → AI identifies words you don't know and explains them in context → Review with spaced repetition until they stick.
🔗 Live Demo: vocab.kaili.dev · 中文文档
Demo account:
test@test.com/123456(Free tier)
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- Dual AI pipeline — Google Cloud NLP tokenizes the article and extracts word lemmas; GPT-4o-mini explains each unfamiliar word based on how it's used in this article, not a generic dictionary definition
- Three-type word classification —
New(first time seen),Extend(known word, new meaning in context),Mastered(AI determines you already know this usage — skipped and not saved) - Anki SM-2 spaced repetition — saved words enter a flashcard queue; four difficulty ratings (Again / Hard / Good / Easy) dynamically compute the next review date
When reading English articles, you often hit a word you sort of know — but the dictionary definition doesn't fit the context. Querying an AI tool works, but it breaks your reading flow.
Vocab Master fixes this: it reads the article for you, filters out words you already know (based on your proficiency level), and has AI explain only the truly unfamiliar ones — in context.
- Set your level — choose from 7 proficiency tiers (Middle School → GRE). The system pre-filters words you already know.
- Paste an article — Google NLP tokenizes the text; GPT-4o-mini explains unfamiliar words based on how they're used in this article, not just generic definitions.
- Review with flashcards — saved words enter an Anki SM-2 spaced repetition queue. Four difficulty ratings (Again / Hard / Good / Easy) dynamically adjust your next review date.
- Known-word whitelist — manually mark domain terms (e.g. tech jargon) so they're always filtered out
- Auth — email + phone number sign-up/login with verification, powered by Better Auth
- Subscriptions — Stripe-powered freemium with monthly/yearly plans and webhook-driven lifecycle management
- Usage quotas — middleware-level enforcement with real-time display and upgrade prompts
- Learning stats — daily new words, review count, accuracy rate, streaks
| Backend | Hono.js on Cloudflare Workers |
| Database | PostgreSQL (Neon) via HTTP + Drizzle ORM |
| Auth | Better Auth (email + phone) |
| AI / NLP | OpenAI GPT-4o-mini + Google Cloud NLP |
| Payments | Stripe (subscriptions + webhooks) |
| Frontend | React 19, React Router v7, TanStack Query, Radix UI |
| Validation | Zod (end-to-end, shared between client and server) |
| Monorepo | pnpm workspaces (api / client / shared) |
| Free | Premium | |
|---|---|---|
| Articles / day | 2 | 50 |
| Max words / article | 1,000 | 5,000 |
| Flashcard review | ✓ | ✓ |
| Price | $0 | $7 / mo · $67 / yr |
MIT