I Used OpenAI + FastAPI to Build a Pet Symptom Checker — Here's the Full Stack Breakdown

I Used OpenAI + FastAPI to Build a Pet Symptom Checker — Here's the Full Stack Breakdown Pet owners panic. It's 11 PM, your dog just ate something suspicious, and Google gives you 47 tabs of conflicting advice ranging from "it's fine" to "call 911." So I built an AI that actually helps. Here's the complete technical breakdown — including the parts that didn't work first. The Problem Most pet health tools are either: Glorified keyword matching ("vomiting" → "go to vet") $100+/month subscription vet chat services Reddit threads from 2014 I wanted something that actually reasons about symptoms, considers species/breed/age, and gives actionable triage advice in plain English. The Stack Frontend: Next.js 14 + Tailwind Backend: FastAPI (Python 3.11) AI: OpenAI GPT-4o with structured outputs DB: Supabase (Postgres + pgvector) Infra: Railway + Vercel The Core: Structured AI Outputs The biggest mistake most devs make with AI health tools? Trusting unstructured text output. Here's the pattern th