The Great GPT Firewall provides a policy-driven gateway for GPT-based applications. It sits between your app and the GPT API, examining each request and response against user-defined JSON-schema policies. With both a command-line interface and easily importable library, you can define rules to block or modify disallowed prompts and outputs, log any violations, and receive real-time alerts. The tool supports extensible rule sets, custom handlers for violation events, and seamless integration into CI/CD pipelines, helping teams maintain content safety and regulatory compliance across diverse AI deployments.