ApexGPT Backend

• Description: Backend API for a simple chat application that stores conversation threads in MongoDB and uses GROQ's chat completions API to generate assistant replies.

🔗 Live Demo: http://ec2-13-60-56-164.eu-north-1.compute.amazonaws.com/

Features

• Store Chats: Saves conversation threads and messages in MongoDB (Thread model).
• Chat Completion: Sends user messages to GROQ API and stores assistant replies.
• REST API: Endpoints to create/read/delete threads and send chat messages.

Prerequisites

• Node.js: v18+ recommended.
• MongoDB: A MongoDB Atlas connection string (or local MongoDB URI).
• GROQ API Key: A valid GROQ API key for calling the chat completions endpoint.

Required Environment Variables

• MONGODB_URI : MongoDB connection string used by Mongoose.
• GROQ_API_KEY : API key for GROQ's chat completions endpoint.

Create a .env file in the project root with:

MONGODB_URI=your_mongodb_connection_string
GROQ_API_KEY=your_groq_api_key

Install Open a PowerShell terminal in the project root and run:

npm install

Run

• Start the server (default port is 8080):

node server.js
# or (if you have nodemon installed globally)
nodemon server.js

The server listens on port 8080 (see server.js).

API Endpoints All routes are prefixed with /api (e.g. http://localhost:8080/api/...).

• POST /api/test

  • Creates a sample thread (for testing). Returns the saved thread document.
  • Body: none (the route creates a sample thread with hardcoded threadId: "abcd").

• GET /api/thread

  • Returns all threads sorted by updatedAt (most recent first).

• GET /api/thread/:threadId

  • Returns the messages array for the specified threadId.

• DELETE /api/thread/:threadId

  • Deletes the thread with the given threadId.

• POST /api/chat

  • Main chat endpoint. Sends user message to GROQ and stores both user and assistant messages in the thread.
  • Body (JSON):
    • threadId (string): unique id for the conversation thread
    • message (string): user's message/prompt
  • Response (JSON): { reply: "assistant reply text" }

Example curl (PowerShell-friendly) for sending a chat:

curl -Method POST -Uri http://localhost:8080/api/chat -ContentType 'application/json' -Body (
	ConvertTo-Json @{ threadId = 'thread-1'; message = 'Hello, world' }
)

Project Structure

• server.js — Express server and MongoDB connection.
• routes/chat.js — All API routes for threads and chat.
• models/Thread.js — Mongoose schema for Thread and nested Message.
• utils/groq.js — Small helper to call GROQ's chat completions API.
• package.json — Project dependencies.

Author

• Nikunj Mehta: https://github.com/Nikunj-Mehta