Most AI applications rely solely on IP-based rate limiting to prevent abuse. Unfortunately, that's only the first line of defense.
In this article, we'll build a production-inspired anonymous identity system using FastAPI, MongoDB, and Beanie that tracks visitors using fingerprints, enforces daily usage limits, prepares for future authentication, and lays the foundation for a scalable AI SaaS.
We'll also see how this integrates cleanly with a multi-provider LLM Router without polluting business logic.
When building AI products, most developers focus on prompts, LLMs, and fancy frontend interfaces.
Very few spend time thinking about what happens before the AI is even called.
