BookTalk

Turn any PDF into an interactive AI conversation. Upload a book, and BookTalk indexes its content so you can discuss it by text or voice — the AI answers grounded in what the book actually says.

Features

• PDF upload & processing — extracts text, chunks it, and generates embeddings for retrieval
• Text chat (RAG) — ask questions about a book; answers are retrieved from the book's own content via vector search
• Voice chat — talk to a book out loud via Vapi AI
• Personal library — track your books, search/filter, and pick up where you left off
• Subscription plans — Free / Standard / Pro tiers with book-count limits, billed via Stripe

Stack

• Next.js 16 (App Router) + React 19
• Better Auth — authentication
• MongoDB Atlas + Mongoose — data storage and $vectorSearch for retrieval
• Vercel Blob — PDF file storage
• Hugging Face Inference — text embeddings
• Vapi AI — voice conversations
• Stripe — subscription billing
• Tailwind CSS + shadcn/base-ui

Getting started

Install dependencies:

npm install

Create a .env.local file with the variables listed in Environment variables below, then run the dev server:

npm run dev

Open http://localhost:3000.

Environment variables

Variable	Purpose
BETTER_AUTH_SECRET / BETTER_AUTH_URL	Better Auth authentication
MONGODB_URI	MongoDB Atlas connection string
BLOB_READ_WRITE_TOKEN	Vercel Blob storage
HUGGINGFACE_API_KEY	Embeddings for RAG search
NEXT_PUBLIC_VAPI_API_KEY / NEXT_PUBLIC_VAPI_ASSISTANT_ID	Voice chat
ELEVENLABS_API_KEY	Voice synthesis (configured in the Vapi dashboard, not read directly by the app)
STRIPE_SECRET_KEY	Stripe API access
STRIPE_WEBHOOK_SECRET	Verifies incoming Stripe webhook events
STRIPE_PRICE_ID_STANDARD / STRIPE_PRICE_ID_PRO	Stripe Price IDs for paid plans
NEXT_PUBLIC_APP_URL	Base URL used for Stripe redirect/callback URLs

For local Stripe webhook testing, run the Stripe CLI:

stripe listen --forward-to localhost:3000/api/stripe/webhook

Testing

npm run test

Deployment

Deployed on Vercel. Remember to register a production Stripe webhook endpoint and set all environment variables (including live-mode Stripe keys, when ready) in the Vercel project settings.