I've been working on Aegis.rs for a bit, and I wanted to share it. It's the first open-source Rust-based LLM security proxy (that I could find, at least).
I kept having the same issue, since existing LLM security tools are either Python libraries you have to manually integrate into your app, or cloud SaaS products that route your traffic through a third party (which you can't control), and i wanted something that just sat in the middle without touching my code or sending prompts anywhere.
So I built a transparent reverse proxy. You point your requests at localhost:8080 instead of your LLM endpoint and, so far, it catches prompt injections, jailbreaks, PII leakage, and other LLM attacks, blocking them before any malicious request even reaches the model. If a request is clean, it forwards it. If it's malicious, it blocks it. Zero code changes.
It runs two layers: a fast heuristic engine with 150+ hand-crafted (expandable) regex rules that runs in under 1ms (thanks to Actix-web), plus an AI judge using Groq for semantic analysis on ambiguous cases.
Can be easily shipped as a single binary with a live dashboard, hot-reloadable rules, and structured JSON logs.
Still v0.1 but it's working well enough for me to share its first version. The heuristic layer is fast enough for prod, and extending the rules is pretty easy.
Would love feedbacks (or contributions lol), especially from anyone dealing with LLMs' security and threat modeling :)