InterVista - AI-Powered Mock Interview Platform

A comprehensive full-stack application for practicing interviews with AI-powered feedback, built with Next.js 14, Express.js, TypeScript, and Firebase Firestore.

🚀 Features

Frontend

• ✨ Modern, responsive UI with Tailwind CSS + shadcn/ui
• 🎨 Smooth animations using Framer Motion
• 🔐 Complete authentication flow (sign-in, sign-up, reset password)
• 📊 Interactive dashboard with session management
• 📝 Text-based interview interface with question-by-question flow
• 📈 AI-generated detailed evaluation with per-question feedback
• 🎯 Animated landing page

Backend

• 🔒 JWT-based authentication with bcrypt password hashing (httpOnly cookies)
• 🗄️ Firebase Firestore database (all collections)
• 📁 Audio file upload support (multer) with magic byte validation
• 🤖 Real AI evaluation with Groq (Llama 3)
• 🎙️ Voice features with OpenAI (Whisper + TTS)
• 🔄 RESTful API with typed responses
• 🛡️ Security with Helmet and CORS

📋 Prerequisites

• Node.js v20+
• npm or yarn
• Firebase project with Firestore enabled
• Groq API key and OpenAI API key

🛠️ Installation

1. Clone the repository

git clone <repository-url>
cd InterVista

2. Backend Setup

cd backend
npm install

Create .env file from the example:

cp .env.example .env

Edit .env with your configuration:

PORT=4000
NODE_ENV=development
FIREBASE_PROJECT_ID=your-project-id
FIREBASE_CLIENT_EMAIL=your-client-email@your-project-id.iam.gserviceaccount.com
FIREBASE_PRIVATE_KEY="-----BEGIN PRIVATE KEY-----\nYOUR_KEY_HERE\n-----END PRIVATE KEY-----\n"
JWT_SECRET=your-super-secret-jwt-key-at-least-64-characters
JWT_EXPIRES_IN=7d
CORS_ORIGINS=http://localhost:3000
GROQ_API_KEY=gsk_your_groq_api_key
OPENAI_API_KEY=sk-your-openai-api_key
SMTP_USER=your-email@example.com
SMTP_PASS=your-smtp-password

Firebase Setup:

1. Create a Firebase project at https://console.firebase.google.com
2. Enable Firestore Database
3. Go to Project Settings → Service Accounts → Generate new private key
4. Copy the project_id, client_email, and private_key values into .env

3. Frontend Setup

cd web
npm install

Create .env.local:

NEXT_PUBLIC_API_URL=http://localhost:4000

🚀 Running the Application

Start Backend

cd backend
npm run dev

Backend runs on http://localhost:4000

Start Frontend

cd web
npm run dev

Frontend runs on http://localhost:3000

📁 Project Structure

InterVista/
├── backend/                 # Express.js + TypeScript backend
│   ├── src/
│   │   ├── config/         # Environment validation
│   │   ├── controllers/    # Auth, Session, Answer controllers
│   │   ├── db/             # Firestore initialization
│   │   ├── lib/            # AI (Anthropic Claude) integration
│   │   ├── middleware/     # JWT auth middleware
│   │   ├── routes/         # API route wiring
│   │   ├── types/          # TypeScript interfaces
│   │   └── server.ts       # Express app entry point
│   └── uploads/            # Audio file storage
│
└── web/                     # Next.js 14 (App Router)
    ├── src/
    │   ├── app/            # App router pages
    │   ├── components/     # React components (shadcn/ui)
    │   ├── contexts/       # Auth context
    │   └── lib/            # API client & utilities
    └── public/             # Static assets

🔐 Authentication Flow

1. User signs up → password hashed with bcrypt (12 rounds)
2. JWT token generated with a JTI and stored securely in an httpOnly cookie
3. Session is maintained via the cookie, which is sent with all Credentials: "include" requests
4. Sign out revokes the JWT using a Firestore blocklist
5. On 401 response → cookie cleared, redirect to sign-in
6. GET /api/auth/me validates token and returns user on page load

🤖 AI Integration

InterVista uses Groq (Llama 3.3) and OpenAI for:

• Question Generation: Groq generates 5 role-specific interview questions based on company, role, target difficulty and persona constraints
• Answer Evaluation: Groq evaluates all answers asynchronously (202 Accepted pattern) and returns:
  • Overall score (0-100)
  • Recommendation (Strong Hire / Hire / Consider / No Hire)
  • Skills assessment (Communication, Technical Knowledge, Problem Solving, Confidence)
  • Per-question feedback with strengths and areas for improvement
• Transcription: OpenAI Whisper transcribes candidate audio responses
• Text-to-Speech: OpenAI TTS brings the interviewer personas to life

📝 API Endpoints

Authentication

Method	Endpoint	Description	Auth
POST	/api/auth/signup	Register new user	No
POST	/api/auth/signin	Sign in user	No
GET	/api/auth/me	Get current user	Yes
POST	/api/auth/reset-password	Request password reset OTP	No
POST	/api/auth/verify-reset	Verify OTP and reset password	No

Sessions

Method	Endpoint	Description	Auth
POST	/api/sessions	Create session + AI questions	Yes
GET	/api/sessions	List user's sessions	Yes
GET	/api/sessions/:id	Get session details	Yes
GET	/api/sessions/:id/questions	Get session questions	Yes

Answers

Method	Endpoint	Description	Auth
POST	/api/answers	Submit answer (multipart)	Yes
GET	/api/answers/evaluation/:sessionId	Get/generate AI evaluation (async 202)	Yes
POST	/api/answers/evaluation/:sessionId/retry	Retry failed evaluation	Yes
POST	/api/auth/signout	Sign out and revoke token	Yes

All responses follow: { data: payload } on success, { error: string } on failure.

🔧 Environment Variables

Backend

Variable	Description	Required
PORT	Server port (default: 4000)	No
NODE_ENV	Environment	No
FIREBASE_PROJECT_ID	Firebase project ID	Yes
FIREBASE_CLIENT_EMAIL	Firebase service account email	Yes
FIREBASE_PRIVATE_KEY	Firebase service account private key	Yes
JWT_SECRET	JWT signing secret	Yes
JWT_EXPIRES_IN	Token expiration (default: 7d)	No
CORS_ORIGINS	Allowed origins (default: localhost:3000)	No
GROQ_API_KEY	Groq API key for Llama 3	Yes
OPENAI_API_KEY	OpenAI API key for TTS/Whisper	Yes
SMTP_USER	SMTP username	No
SMTP_PASS	SMTP password	No

Frontend

Variable	Description	Required
NEXT_PUBLIC_API_URL	Backend API URL	Yes

📦 Tech Stack

Layer	Technology
Frontend	Next.js 14 (App Router), React 18, TypeScript
Styling	Tailwind CSS v3, shadcn/ui, Framer Motion
Backend	Express.js, TypeScript, Node.js v20+
Database	Firebase Firestore
Auth	JWT in httpOnly Cookies, bcrypt
AI (LLM)	Groq (llama-3.3-70b-versatile)
AI (Audio)	OpenAI (whisper-1, tts-1)
File Upload	Multer

---

Made with ❤️ by the InterVista Team