Building a Multi-Model AI Chat Application with MERN Stack

I'll create a full MERN stack application that allows you to chat with different AI models including OpenAI, Anthropic Claude, and Perplexity. This application will use the AI SDK, which provides a unified interface for working with different AI models 1.

How It Works

This MERN stack application allows you to chat with different AI models through a unified interface. Here's a breakdown of the key components:

Frontend (React/Next.js)

• A modern chat interface with model selection dropdown
• User authentication system with login and registration
• Settings page to manage API keys for different providers
• Conversation history and management

Backend (Node.js/Express with Next.js API Routes)

• API routes for handling chat requests to different AI models
• User authentication and registration
• Conversation and message storage in MongoDB

AI Integration

• Uses the AI SDK to provide a unified interface for different AI models 1
• Supports OpenAI (GPT-4o), Anthropic Claude, and Perplexity models 234
• Streams responses in real-time for a better user experience

Database (MongoDB)

• Stores user information
• Saves conversation history
• Manages API keys securely

Key Features

1. Model Switching: Easily switch between different AI models (OpenAI, Claude, Perplexity) 1
2. Real-time Streaming: Responses stream in real-time for a better chat experience 5
3. User Authentication: Secure login and registration system
4. Conversation History: Save and retrieve past conversations
5. API Key Management: Securely manage your API keys for different providers
6. Responsive Design: Works on desktop and mobile devices

Setup Instructions

1. Clone the repository
2. Install dependencies with npm install
3. Set up a MongoDB database

4. Create a .env.local file with the following variables:

   MONGODB_URI=your_mongodb_connection_string NEXTAUTH_SECRET=your_nextauth_secret NEXTAUTH_URL=http://localhost:3000
5. Run the development server with npm run dev
6. Add your API keys in the settings page for each provider you want to use

Environment Variables

You'll need to set up the following environment variables:

API Keys

For this application to work properly, you'll need API keys from the following providers:

1. OpenAI API Key: Get it from OpenAI Platform
2. Anthropic Claude API Key: Get it from Anthropic Console
3. Perplexity API Key: Get it from Perplexity AI

You can add these keys in the Settings page of the application.

Extending the Application

Here are some ways you could extend this application:

1. Add more AI model providers like Groq, Mistral, or xAI
2. Implement conversation summarization
3. Add file upload capabilities for multi-modal models
4. Implement a system to compare responses from different models
5. Add a feature to export conversations

Troubleshooting

If you encounter any issues:

1. Make sure your MongoDB connection string is correct
2. Verify that your API keys are valid and have sufficient credits
3. Check the browser console and server logs for any errors
4. Ensure you're using Node.js version 18 or higher

Please make sure to add the following environment variables to your project:

I'll fix the SessionProvider error by adding it to the root layout. This is needed for the useSession hook to work properly throughout the application.

This fix addresses the deployment error by:

1. Creating a new client component called Providers that wraps the application with the SessionProvider from next-auth/react
2. Importing and using this component in the root layout

The SessionProvider is essential for the authentication system to work properly, as it makes the session data available throughout the application via the useSession hook. Without it, components that use useSession (like our settings page and authentication-protected routes) would throw errors.

Now the application should deploy successfully, with the authentication system working as expected.