ReplyMate — Backend

AI-powered reply suggestions for your DMs. ReplyMate reads the context of a conversation plus notes you've saved about a contact, and suggests a few natural replies — you decide if you want to use them. Nothing is sent automatically.

Stack

• Node.js + Express
• MongoDB (Mongoose)
• JWT authentication
• Groq API (Llama 3.3 70B) for generating suggestions

Features

• Secure signup/login with hashed passwords (bcrypt) and JWT-protected routes
• Per-user contact profiles — save notes and a tone preference for each person you message
• AI-generated reply suggestions based on recent conversation + contact context
• No message content is ever stored — only that a suggestion was requested, for usage tracking

Getting Started

1. Install dependencies

npm install

2. Set up environment variables

Copy the example file and fill in your own values:

cp .env.example .env

Variable	Description
PORT	Port the server runs on (default: 5000)
MONGO_URI	MongoDB connection string
GROQ_API_KEY	API key from console.groq.com/keys
JWT_SECRET	Any long random string, used to sign auth tokens

3. Run the server

npm run dev

Visit http://localhost:5000/api/health — you should see a success response.

API Overview

Auth — /api/auth

Method	Route	Description
POST	/signup	Create a new account
POST	/login	Log in, returns a JWT

Contacts — /api/contacts (requires Authorization: Bearer <token>)

Method	Route	Description
POST	/	Create a contact profile
GET	/	List your contacts
PUT	/:id	Update a contact
DELETE	/:id	Delete a contact

Suggestions — /api/suggest (requires Authorization: Bearer <token>)

Method	Route	Description
POST	/	Get 3 AI-generated reply suggestions for a conversation

Example request body:

{
  "contactId": "664f...",
  "messages": [
    { "sender": "them", "text": "You free this weekend?" },
    { "sender": "me", "text": "Depends, what's up?" }
  ]
}

Notes

• Passwords are hashed via a Mongoose pre("save") hook — never stored in plain text.
• Every contact/suggestion query is scoped to req.user.id, so users can only ever access their own data.
• Message content sent to /api/suggest is used only to generate the response — it isn't persisted in the database.

Roadmap

• Chrome extension to scrape conversation context from WhatsApp Web / Instagram DMs
• Rate limiting per user/plan
• OTP-based email verification (not yet implemented — MVP currently uses plain email/password)