Derp AI — AI Model Comparison Chat App

Derp AI is a real-time chat platform that streams responses from multiple AI models at once, enabling side-by-side model comparison. It runs on a full-stack TypeScript monorepo using NestJS for the backend and Vite + React for the frontend and pnpm for repo and package management.

🌐 Deployed here: https://derp.ai.petarzarkov.com/

🔑 Key Features

• Simultaneous AI Responses – Sends each prompt to 4 AI models in parallel and streams all responses back in real-time.
• Deployed on Google Cloud Run – Scalable, serverless backend powered by NestJS - websockets, passport session, express session store + cookies, helmet (cqrs), cors
  • Session store module - services/server/app/modules/session/session.store.ts, basically https://www.npmjs.com/package/connect-pg-simple but the NestJS way
  • Redis used for caching your latest 10 prompts and answers
• Fast Frontend – Built with Vite, React, and Chakra UI.
• Secure Auth – OAuth logins via Google, LinkedIn, and more.
• Extendable AI Support – Easily plug in more models.
• CI/CD - versioning, docker, slack notifications, cloud logs

🧠 Current Models (can be extended)

• gemini-2.0-flash
• gemini-2.5-pro-exp-03-25
• llama-3.3-70b-versatile
• deepseek/deepseek-chat-v3-0324:free

📦 Monorepo Structure

• services/common – Shared types
• services/server – NestJS backend (WebSockets + AI orchestration)
• services/web – Vite + React frontend
• services/mobile – React Native placeholder (not yet implemented) branch for it here
• services/desktop – Electron placeholder (not yet implemented) branch for it here

🚀 Getting Started

Prerequisites

• Node.js ≥ 22
• pnpm ≥ 10
• Docker + Docker Compose
• PostgreSQL (or use Docker)
• Git

Setup

git clone https://github.com/petarzarkov/derp.ai.git
cd derp.ai
pnpm install
cp .env .env.dev  # Then fill in keys for Gemini, Groq, OpenRouter, etc.

Development

• Start redis + DB with Docker

docker-compose up -d

# Run both frontend and backend in watch mode
pnpm dev

Or separately:

pnpm --filter server dev
pnpm --filter web dev

🐳 Docker Deployment

To build and run the backend manually via Docker:

docker build -t derpai-server .
docker run -p 3033:3033 --env-file .env derpai-server