StudyKit

Upload what you are actually studying, and it asks you the questions.

Built because tools like Thea, Quizlet and Knowt all put the useful parts — unlimited questions, practice tests, no waiting — behind a paywall or a daily cap. This runs on your own free API key, so there is no cap and no bill.

What it does

Study kits. Paste notes or drop in a PDF. It reads the material once and builds flashcards, a revision guide and a pool of questions from it. PDFs are parsed in your browser, so the file itself never leaves your machine — only the extracted text is sent on.

Smart Study. Open-ended questions you answer by typing. Each answer is marked on understanding rather than wording, told what you left out, and given the correct answer. Difficulty climbs when you are scoring above 80% and drops below 50%, and the question picker weights towards concepts you keep getting wrong.

Flashcards. Scheduled with SM-2, the spaced-repetition algorithm behind Anki. Cards you know stretch further apart; cards you miss come back in ten minutes.

Practice tests. Multiple choice, 5 to 25 questions, timed and marked at the end like a real paper. The wrong options are written to be plausible rather than obvious.

Revision guide. The material condensed per concept, with a section contrasting the ideas that are easy to mix up.

Everything comes from your own uploads. The prompts tell the model to say when the material does not cover something instead of filling the gap from elsewhere.

Running it

1. Supabase

Create a project at supabase.com (free tier is enough), then run the two files in supabase/migrations/ in the SQL editor, oldest first. They create the tables, the row-level-security policies and two views.

From Project Settings → Data API, copy the project URL and the publishable key.

2. Gemini key

Get a free key at aistudio.google.com/apikey. No credit card. The free tier has a daily request limit that one person is unlikely to reach; if you do, gemini-3.5-flash-lite has a larger quota.

3. Environment

cp .env.example .env.local   # then fill it in
npm install
npm run dev

Variable	Needed	What it is
NEXT_PUBLIC_SUPABASE_URL	yes	Your Supabase project URL
NEXT_PUBLIC_SUPABASE_PUBLISHABLE_KEY	yes	Publishable key, safe in the browser
GEMINI_API_KEY	yes	Server-side only. Never prefix with NEXT_PUBLIC_
GEMINI_MODEL	no	Defaults to gemini-3.8-flash
AI_PROVIDER	no	gemini (default) or anthropic
ANTHROPIC_API_KEY	no	Only if AI_PROVIDER=anthropic

Visit /api/health to check what the server can see. It reports whether each variable is set, never its value, and is reachable without signing in so it still works when the app is misconfigured.

4. Sign-up

By default Supabase emails a confirmation link before the first sign-in. For a personal instance it is easier to turn that off: Authentication → Sign In / Providers → Email → Confirm email. Sign-up then logs you straight in. The app handles both.

Deploying

Import the repo on Vercel, add the same environment variables, deploy. The free Hobby plan covers it; AI routes are capped at the 60-second function limit.

Swapping the AI

Nothing outside lib/ai/provider.ts knows which model is in use. Everything calls getProvider(), which returns something with generateJSON and generateText. Gemini and Claude are implemented; adding Groq or a local model means writing one more class and a line in the factory.

Claude is left off by default because the Claude API is billed per token and is separate from a Claude.ai subscription — a Pro plan does not include API access.

How it is built

• Next.js 16 (App Router, Turbopack). Auth is refreshed in proxy.ts, which is what middleware is called in 16.
• Supabase for auth and Postgres. Every table carries user_id and an RLS policy, so a user can only ever read or write their own rows — enforced by the database, not by application code.
• Self-hosted fonts (app/fonts/) rather than Google Fonts, so no third-party request on load and no build-time dependency on a CDN.
• No answer reaches the browser early. Smart Study stores the expected answer on a pending row server-side and marks against it; practice tests keep the correct options server-side until you submit. Neither is readable from devtools.

app/
  api/            route handlers: kit building, questions, marking, tests
  kits/[id]/      study · cards · test · guide
lib/
  ai/provider.ts  the only file that knows about a model vendor
  ai/study.ts     prompts and response schemas
  srs.ts          SM-2 scheduling
  supabase/       browser, server and proxy clients
supabase/migrations/

Tests

npm run typecheck
npm run lint
npm run build

lib/srs.ts is checked against the SM-2 specification (interval progression 1 → 6 → ×ease, the 1.3 ease floor, lapse handling) and the Gemini provider against a stand-in API covering the response shape and every HTTP failure.

Licence

MIT.