builp

Learn by building. Write, generate, and work through courses consisting of written lessons, runnable code practice, and interactive activities.

Live at builp.kdnth.co.

Stack

• Frontend: React, TypeScript, Vite, Mantine
• Backend: FastAPI, SQLAlchemy, Alembic, Postgres
• Auth: Neon Auth
• Course generation: LangGraph, provider-tiered LLM routing (Anthropic, OpenAI, Groq, xAI, Mistral, Gemini, Ollama, DeepSeek)

Project layout

frontend/   React app
backend/    FastAPI app, database, course generation
docs/       Design notes and plans

Setup

You need:

• Node 20 or later
• Python 3.12 or later, and uv
• A Neon project, with Neon Auth turned on
• An Anthropic API key, for the server-managed free generation credit path

Backend

cd backend
cp .env.example .env
# fill in DATABASE_URL, NEON_AUTH_URL, ANTHROPIC_API_KEY
uv sync
uv run alembic upgrade head
uv run uvicorn app.main:app --reload --port 8000

Details on the API, tests, and migrations: backend/README.md.

Frontend

cd frontend
cp .env.example .env.local
# fill in VITE_NEON_AUTH_URL
npm install
npm run dev

Open http://localhost:5173.

Auth configuration (Neon)

These auth flows depend on Neon Auth settings in your Neon project:

• Turn on Sign-up with Email.
• Turn on Verify at Sign-up (recommended for production).
• For verification links, configure a custom email provider. With Neon's shared provider, use verification codes.
• Add your app origins to trusted domains (for example http://localhost:5173 and your production domain) so auth redirects are accepted.

Password reset is available when email authentication is enabled.

Generation modes

Users can choose one of two generation paths when creating a course:

• Free credit: one generation per rolling 24-hour window, using the server-managed Anthropic key.
• Provider API key: bypasses the daily free-credit limit by supplying an anthropic, openai, groq, xai, mistral, gemini, ollama, or deepseek API key. The key is used in-memory for that generation request only and is not written to the database or logs.

Default model tier maps and provider endpoint overrides are documented in backend/README.md.

Roadmap

• Code practice support for more languages, not just JavaScript
• Code practice IDE improvements: type hints, tab indenting, custom test cases
• More interactive activity types

Contributing

See CONTRIBUTING.md.

License

MIT. See LICENSE.