KI-Shield is a privacy-compliant proxy for large language models (LLMs) that automatically detects and pseudonymizes personally identifiable information before requests reach external AI providers like OpenAI, Anthropic, or Google. With 43 specialized detection methods covering German-specific formats including IBAN, tax ID, health insurance numbers, and GDPR Article 9 special categories, the system ensures no personal data leaves the company network. AI responses are also scanned for newly generated PII. Every transaction is logged in a tamper-proof audit chain with Ed25519 and post-quantum ML-DSA-65 dual signatures, hash-chained via SHA-256, and anchored daily on the Polygon blockchain. A Zero-Knowledge architecture ensures that even the operator cannot access customer data. Patent applications filed with the German Patent and Trademark Office (DPMA). Built and operated in Germany.