Codegraph

How I Built CodeGraph: A Living Knowledge Graph That Tells You What Breaks Before You Break It Built for HACKHAZARDS '26 — powered by Neo4j AuraDB, tree-sitter, Groq LLaMA, and Next.js The Problem That Frustrated Me Every developer knows this feeling. You join a new codebase. There are 50,000 lines of code. Your manager says "just fix this small bug in the authentication module." You make the change. You push. And suddenly three completely unrelated features are broken — a payment flow, a notification system, and a dashboard widget you've never even looked at. You spend the next four hours tracing function calls manually, reading code you've never seen, trying to understand why changing one function in auth.py broke something in notifications.py on the other side of the codebase. This is not a rare experience. According to JetBrains' developer survey, engineers spend 58% of their time reading and understanding code — not writing it. One wrong change in a large codebase can cost hours of debugging, failed deployments, and frustrated users. I built CodeGraph to solve this. Not with another AI chatbot that guesses at your code. With a real, queryable knowledge graph that actually understands how your codebase is connected. What CodeGraph Does CodeGraph takes any public GitHub repository URL and within seconds: Parses every function in the codebase using tree-sitter Maps every call relationship between functions as a directed graph Stores everything in Neo4j AuraDB as a live knowledge graph Lets you ask questions in plain English — answered by AI grounded in real graph data The result: paste a GitHub URL, see your entire codebase as an interactive graph, click any function, and instantly know what breaks if you change it. The Tech Stack Here's what I used and why each choice mattered: Backend: Python + FastAPI (REST API server) Neo4j AuraDB (graph database — the core of everything) tree-sitter (AST parser for Python, JS, TS, TSX) Groq API with LLaMA 3.3 70B (free-tier L