Multi-LLM courtroom simulation with RAG-powered legal arguments, real-time scoring, and AI judges
LexAI is an interactive Greek courtroom simulator powered by multiple large language models. Each legal role — defense attorney, prosecutor, judge, and witness — is assigned a dedicated LLM with automatic fallback routing. Arguments are grounded in Greek law via a ChromaDB RAG pipeline, scored in real-time, and streamed live to the frontend.
You can play as the defense attorney yourself, or sit back and watch AI vs AI unfold.
| Component | Technology |
|---|---|
| Frontend | React 19, TypeScript, Vite, Tailwind CSS v4 |
| State | Zustand |
| Routing (frontend) | React Router DOM v7 |
| Backend | FastAPI, Python 3.11 |
| LLM Orchestration | LangChain 0.3 |
| LLM Providers | Anthropic Claude, OpenAI GPT-4o-mini, Ollama |
| Vector Store | ChromaDB + sentence-transformers |
| Streaming | Server-Sent Events (SSE) |
| Rate Limiting | SlowAPI |
| Containerization | Docker + Docker Compose |
- ⚖️ Multi-role courtroom — Defense, Prosecution, Judge, Witness each powered by different LLMs
- 🔀 Automatic fallback chains — If a provider fails, the chain falls back seamlessly
- 📚 RAG legal context — Greek law excerpts retrieved via ChromaDB, injected into every argument
- ⚡ SSE streaming — Arguments stream token by token, courtroom-style
- 🧠 LLM-as-judge scoring — Each argument scored 0–10 with structured output (no JSON parsing)
- 🎮 Two modes — Play as defense or watch AI vs AI
- 🏛️ Authentic Greek UI — All interface text in Greek, Cinzel + Source Serif 4 typography
graph TD
FE[React Frontend<br/>Vite + Zustand] -->|SSE Stream| API[FastAPI Backend]
API -->|Role routing| LLM[LLM Router]
LLM -->|defense| ANT[Anthropic Claude<br/>claude-sonnet-4-5]
LLM -->|prosecution| OAI[OpenAI<br/>gpt-4o-mini]
LLM -->|judge| OLL[Ollama<br/>llama3.2]
LLM -->|fallback| ANT
API -->|retrieval| RAG[ChromaDB RAG<br/>sentence-transformers]
RAG -->|legal context| LLM
API -->|scoring| SCR[Scoring Engine<br/>structured output]
SCR -->|ScoreResult| FE
- Python 3.11+
- Node.js 20+
- Anthropic API key and/or OpenAI API key
git clone https://github.com/GiorgosPanagopoulos/lexai
cd lexai
cp backend/.env.example backend/.env
# Edit backend/.env with your API keys
docker compose up --build- Frontend: http://localhost:5173
- Backend: http://localhost:8000
Backend:
cd backend
python -m venv venv
source venv/bin/activate # Windows: venv\Scripts\activate
pip install -r requirements.txt
cp .env.example .env # fill in your API keys
uvicorn backend.main:app --reload --host 0.0.0.0 --port 8000Frontend:
cd frontend
npm install
npm run devΥπεράσπιση (Παίξε) — You play as the defense attorney. Type your arguments in Greek, the Prosecution and Judge respond automatically via AI.
Παρατήρηση AI vs AI — Watch Defense, Prosecution, and Judge debate autonomously. Pure AI courtroom drama.
After each side has argued at least 3 times, the "Αίτημα Ετυμηγορίας" button activates. The Judge LLM reviews the full transcript and delivers a structured verdict: GUILTY or NOT GUILTY.
- Multiplayer mode (2 users argue opposing sides)
- More case scenarios across different legal domains
- Full Greek law RAG with real Hellenic legal texts
- Appeal system (second trial with new evidence)
- Voice input for arguments
I build things I'd trust with something that matters.
⚡ Built by — Georgios Panagopoulos — Full-Stack Developer
☕ Powered by mass amounts of caffeine & mass amounts of curiosity.