I Built a Local AI Firewall and made it Open Source Because Nobody Else Was Going To ! | HackerNoon

Most AI apps send raw user input straight to OpenAI with zero filtering. I got tired of seeing it and built Sentinel Protocol, an open source local proxy with 81 security engines that scans every LLM request and response. It blocks PII, catches prompt injections, detects hallucinated URLs in model output, and handles MCP poisoning for AI agents. One command to start. Change one line in your SDK. 52,069 lines of code, 9 dependencies, MIT license. No cloud, no telemetry, everything runs on your machine.