🛡️ ShadowLink

Privacy-First Settlement Layer for Business on Solana.

Built with ShadowWire SDK, NestJS, React, and MongoDB.

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📽️ Demo Showcase

Click to watch the full walkthrough demonstrating Mainnet transactions

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💡 The Problem & Solution

Businesses need privacy, but Blockchains are public.

• Competitors can see how much you pay suppliers.
• Employees can see each other's salaries.
• Bidders can see rival offers in tenders.

ShadowLink is a comprehensive B2B platform enabling confidential transactions for public procurement, supply chain invoices, and corporate payroll using Zero-Knowledge Proofs (Bulletproofs) on Solana Mainnet.

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🚀 Key Features

1. 🏛️ ShadowTender (Public Procurement)

• Blind Bidding: Companies submit encrypted bids. Competitors cannot see amounts, preventing bid sniping and collusion.
• Workflow: Create Tender → Deposit & Bid → Select Winner → Submit Work → Private Payment.
• Verification: ZK-Proofs ensure the bid is valid without revealing the value on-chain.

2. 📦 SupplyChain Zero (Invoicing)

• Private B2B Payments: Suppliers issue invoices; buyers pay using USD1 via ShadowWire.
• Address Book: Manage verified business contacts.
• Flexible Settlement: Choose between Internal (Shielded-to-Shielded) or External (Shielded-to-Public) transfers.

3. 👥 ShadowPayroll (Corporate Salaries)

• Batch Processing: Pay salaries to hundreds of employees with privacy.
• Salary Confidentiality: Employees receive funds, but the amount is hidden from on-chain observers and colleagues.

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🛠️ Tech Stack

• Blockchain: Solana (Mainnet), ShadowWire SDK v1.1.5 (WASM), USD1 Token.
• Frontend: React, Vite, Tailwind CSS, Lucide Icons, React Hot Toast.
• Backend: NestJS (Node.js), Mongoose.
• Database: MongoDB (Cloud Atlas).
• Wallet: Phantom (via Solana Wallet Adapter).

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⚙️ Installation & Setup

Prerequisites

• Node.js (v18+)
• MongoDB (Local or Atlas Connection String)
• Phantom Wallet (Solana Mainnet)

1. Clone Repository

git clone https://github.com/denisthe12/shadowlink.git
cd shadowlink

2. Configure Environment Variables

Create .env files in both client and server directories.

Server (server/.env):

MONGO_URI=mongodb://127.0.0.1:27017/shadowlink_db
PORT=3000

Client (client/.env):

# Your Backend URL
VITE_API_URL=http://localhost:3000/api

# Solana RPC (Helius/QuickNode recommended for Mainnet)
VITE_RPC_URL={ADDRESS_RPC}

RPC Provider Options: For stable Mainnet performance (especially for Deposits), we recommend using a dedicated RPC with an API Key:

• Helius: https://mainnet.helius-rpc.com/?api-key=YOUR_API_KEY - Get free API key
• Alchemy: https://solana-mainnet.g.alchemy.com/v2/YOUR_API_KEY - Get free API key
• QuickNode: https://YOUR_ENDPOINT.solana-mainnet.quiknode.pro/YOUR_API_KEY/ - Get free API key

3. Install Dependencies

Backend:

cd server
npm install

Frontend:

cd client
npm install

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🏃‍♂️ Running the Project

You need to run both Backend and Frontend terminals.

Terminal 1: Backend (NestJS)

cd server
npm run start:dev

Server will start on http://localhost:3000

Terminal 2: Frontend (Vite)

cd client
npm run dev

Client will start on http://localhost:5173

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🧪 Demo & Usage Guide

1. Connect Wallet

• Switch Phantom to Mainnet.
• Ensure you have some SOL for gas and USD1 tokens.

2. Deposit (Shielding Funds)

• Click "Deposit" in the header.
• Enter amount (min 5 USD1).
• Approve transaction. This moves funds into the ShadowWire Shielded Pool.

3. Creating a Private Invoice

• Go to Supply Chain Invoices.
• Click New Invoice.
• Select Contact (Bill To) and choose Type: External (or Internal if registered).
• Enter Amount and send.
• Switch user (or use another wallet) to Pay.
• Click Pay Now.
• Result: You will see a tx_signature proving the transaction was broadcasted to Solana Mainnet via the ShadowWire Relayer.

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🏆 Hackathon Tracks

• Best USD1 Integration: Fully implemented USD1 as the primary settlement token.
• Best Use Case: Solves real-world privacy problems for B2B (Tenders, Payroll).

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_{Built with ❤️ for Radr Labs Hackathon 2026}