I Built a PII Firewall for LLMs in a Weekend (and Caught My Own Leak)
A developer built a PII firewall for LLM interactions to prevent sensitive data from being sent to cloud-based models. The system, implemented using FastAPI and Microsoft Presidio, scans prompts before they reach models like GPT-4o, blocking any that contain personally identifiable information or violate defined policies. This approach ensures compliance with regulations like GDPR by preventing data exfiltration rather than just logging it. AI
IMPACT Enables developers to build more compliant LLM applications by preventing accidental PII leakage to third-party models.