The backend is a Node.js REST API (Express or NestJS) backed by PostgreSQL through Prisma. The core schema covers users, GPUs, wishlists, carts, cart items, orders, order items, and builds. Each GPU record stores brand, series (GTX or RTX), architecture, release date, MSRP, CUDA cores, memory size and type, bus width, and TDP. MSRP is stored separately from the live selling price, which matches the app's "launch price vs. market price" approach, and all money values are stored as integer cents to avoid rounding errors. Endpoints support search, brand, series, and year-range filtering (GET /gpus?series=RTX&yearFrom=2016&yearTo=2026), product details, cart and wishlist actions, and order history. Authentication uses JWT with refresh tokens, images are served through a CDN, and Stripe handles checkout.