NxtGen Hack

Real-Time Invoice Verification & Fraud Intelligence Platform

An API-first infrastructure platform that prevents duplicate invoice financing across banks and NBFCs using cryptographic hashing, AI-powered fraud detection, and an immutable cross-lender audit registry.

📖 Full Documentation · 🏗️ Architecture · 📡 API Reference · � SDK Guide

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✨ What It Does

In Indian trade finance, a supplier can present the same invoice to multiple lenders simultaneously to fraudulently obtain multiple loans. NxtGen Hack solves this with a sub-second verification checkpoint that every lender calls before approving financing.

Vendor submits invoice → Lender calls /api/invoices/verify → System responds in < 100ms
                                         │
                          ┌──────────────┼──────────────────┐
                          ▼              ▼                   ▼
                    SHA-256 Hash    Redis Duplicate     AI Fraud Score
                    Fingerprint     Lock (< 2ms)       (IsolationForest)
                          │              │                   │
                          └──────────────┴───────────────────┘
                                         │
                              VERIFIED / DUPLICATE_DETECTED
                              REJECTED_HIGH_RISK

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🏗️ Architecture

Three services communicate over HTTP:

Service	Stack	Port
Frontend	React 19, TypeScript, Vite, TailwindCSS	5173
Node.js API	Express 4, TypeScript, PostgreSQL, Redis	5001
AI Service	FastAPI, scikit-learn, Pydantic v2	8000

→ See architecture.md for the full system diagram and request flows.

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🚀 Quick Start (One-Click Setup)

The entire NxtGen platform is containerized for sub-second deployment. Ensure you have Docker and Docker Compose installed.

# Clone the repository
git clone https://github.com/ThelastC0debenders/nxtgen-hack.git
cd nxtgen-hack

# Run the automated setup script
chmod +x setup.sh
./setup.sh

What this does:

1. Generates .env files with secure defaults.
2. Boots PostgreSQL, Redis, Node Backend, Python AI, and Frontend.
3. Automatically generates the dataset and trains the AI model.
4. Initializes the database schema.

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🛠️ Manual Setup (Alternative)

Prerequisites: Node 18+, Python 3.10+, PostgreSQL 14+, Redis 7+

# 1. Backend
cd backend && npm install
cp .env.example .env        # Fill in DB, Redis, JWT, AI token
npx ts-node init-db.ts      # Create tables
npm run dev                  # http://localhost:5001

# 2. AI Service
cd backend-ai-fastapi && pip install -r requirements.txt
python -m app.training.generate_dataset
python -m app.training.train_model
uvicorn app.main:app --port 8000 --reload

# 3. Frontend
cd frontend/Frontend && npm install && npm run dev   # http://localhost:5173

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📦 SDK & Integration

The easiest way to integrate NxtGen into your lending or vendor backend is via our API wrappers. We provide comprehensive documentation for both Node.js and Python.

👉 Read the full SDK & Integration Guide

Node.js Example (Axios):

import { NxtGenClient } from './sdk';

const client = new NxtGenClient('https://api.nxtgen.xyz', 'lendor@gmail.com', 'securepass');

async function approveCapital(invoice) {
  const result = await client.verifyInvoice({
    ...invoice,
    buyerGSTIN: "33BBBB2222B1Z2" 
  });

  if (result.status === 'VERIFIED') {
    console.log('Safe to proceed with loan!');
  }
}

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🎭 Demo Credentials

Role	Email	Password
🛡️ Admin	admin@gmail.com	1234567890
🏦 Lender	lendor@gmail.com	0987654321
📦 Vendor	vendor@gmail.com	1234567890

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⚡ Core Features

Feature	How
Sub-second verification	Redis SETNX duplicate lock resolves in < 2ms
AI fraud scoring	Isolation Forest (60%) + deterministic rule engine (40%)
Zero-knowledge registry	Only SHA-256 hashes stored — no raw invoice data shared cross-institution
Immutable audit trail	Hash-chained audit_logs table — tamper-proof by design
Role-based access	Per-route RBAC middleware for ADMIN, LENDER, VENDOR
Graceful degradation	System runs if AI service is unavailable (falls back to score = 0)
Lender financing actions	Finance or Reject invoices directly from dashboard

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📁 Repository Structure

nxtgen-hack/
├── backend/              Node.js + Express API (TypeScript)
├── backend-ai-fastapi/   Python FastAPI ML service
├── frontend/Frontend/    React SPA (TypeScript + TailwindCSS)
└── docs/                 Full documentation
    ├── index.md          Project overview & quick start
    ├── architecture.md   System design & request flows
    ├── sdk-guide.md      Node.js & Python SDK wrappers
    └── api-reference.md  All endpoints, request/response examples

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📊 Invoice Lifecycle

PENDING_VERIFICATION  →  VERIFIED  →  FINANCED
                      →  REJECTED_HIGH_RISK
                      →  DUPLICATE_DETECTED
                      →  REJECTED_BY_LENDER
                      →  CLOSED

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📚 Documentation

Doc	Description
index.md	Project overview, problem, capabilities, demo creds
architecture.md	System diagram, all request flows, repo tree
sdk-guide.md	Node.js and Python SDK wrappers & Integration
api-reference.md	Every endpoint with examples and error codes

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🛠️ Tech Stack

Backend

• Express 4 · TypeScript 5.7 · jsonwebtoken · pg · redis · axios

AI Service

• FastAPI · Uvicorn · scikit-learn (IsolationForest) · Pydantic v2 · joblib · pandas

Frontend

• React 19 · TypeScript 5.9 · Vite 7 · TailwindCSS 4 · React Router v7 · Recharts · Lucide React

Infrastructure

• PostgreSQL 14 (invoices, audit_logs, users)
• Redis 7 (history cache + distributed locks)

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Built with ❤️ by Team ThelastC0debenders