Defund — Decentralized Crowdfunding on Ethereum (Sepolia)

Create impactful campaigns, discover causes, and fund transparently using MetaMask on the Sepolia testnet.

Built with Solidity · Remix · React + Vite · Cloudflare Workers · MetaMask

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Overview

Defund is a non‑custodial, decentralized crowdfunding platform. Campaigns are created and funded directly on Ethereum (Sepolia testnet) via MetaMask, ensuring transparency and on‑chain accountability. An integrated AI helper refines campaign inputs to make titles and descriptions more impactful.

Key Features

• Create campaigns with title, description, target amount, deadline, and image
• Fund campaigns using your MetaMask wallet (Sepolia ETH for testing)
• AI assist to improve your campaign content with one click
• View all campaigns on a dashboard and drill into details
• Live Ethereum price chart with INR conversion (ETH ↔ INR)

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Screenshots

Dashboard — browse active campaigns	Campaign details — fund with MetaMask
Create campaign — AI enhances content	ETH price chart — convert ETH ↔ INR

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Tech Stack

• Smart Contracts: Solidity (deployed via Remix to Sepolia)
• Wallet: MetaMask (Browser extension)
• Frontend: React + Vite
• AI Helper: Cloudflare Worker (HTTP API)
• Price + Conversion: CoinGecko API (demo environment)
• Media: Unsplash API for images

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Architecture

React (Vite) ───────────▶ MetaMask ───────────▶ Ethereum (Sepolia)
   │                         ▲                         ▲
   │                         │                         │
   │    POST /enhance-campaign│                         │
   ├──────────▶ Cloudflare Worker (AI)                  │
   │                                                 Read/Write
   │                              ───────────▶ Defund Smart Contract
   │
   ├──────────▶ CoinGecko (ETH price, INR conversion)
   └──────────▶ Unsplash (campaign images)

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Prerequisites

• Node.js 18+ and npm
• MetaMask installed in your browser
• Sepolia test ETH in your MetaMask account
• A deployed Defund contract address on Sepolia

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Environment Setup

Create a .env file in the client folder with the following variables:

# Sepolia Defund contract address (from your Remix deployment)
VITE_CONTRACT_ADDRESS=0xYourSepoliaContractAddress

# Unsplash API access key (for campaign images)
VITE_UNSPLASH_ACCESS_KEY=your_unsplash_access_key

# CoinGecko demo API key (for ETH price + conversion)
VITE_COINGECKO_API_KEY=your_coingecko_demo_key

Notes:

• Contract address is read in src/utils/connectToWallet.js.
• Unsplash key is used by src/api/unsplashInstance.js.
• CoinGecko key is used by src/utils/getEthPrice.js (demo environment).
• The AI helper is configured to call a Cloudflare Worker at https://ai-worker.defund-ai.workers.dev via src/api/aiWorkerInstance.js. If you deploy your own worker, update that base URL accordingly.

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Run Locally

From the client directory:

npm install
npm run dev

Build and preview:

npm run build
npm run preview

The app expects MetaMask to be available in the browser and your network set to Sepolia.

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Pages

1. Dashboard

   • Lists all campaigns pulled from the Defund smart contract.
   • Click a campaign to view details, donators, and funding history.

2. Create Campaign

   • Input title, description, target amount (ETH), deadline, and image URL.
   • Use the “AI” button to refine your content for better impact.
   • Submits createCampaign to the Defund contract via MetaMask.

3. Ethereum Page

   • Live ETH price chart.
   • Simple ETH ↔ INR conversion powered by CoinGecko.

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Smart Contract Workflow

• Deploy the Defund contract to Sepolia using Remix.
• Copy the deployed address into VITE_CONTRACT_ADDRESS.
• The frontend reads campaigns via getCampaigns, creates new ones via createCampaign, and funds via donateToCampaign using MetaMask/ethers.

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Contract Interface (Frontend)

Core functions used by the client:

• getCampaigns — fetches all campaigns (owner, title, description, target, deadline, amountCollected, image)
• createCampaign — creates a new campaign (writes on-chain)
• donateToCampaign — funds a campaign with ETH
• getDonators — returns donors and donation amounts for a given campaign
• numberOfCampaigns — returns total count

Implementation references:

• Connect and ABI: client/src/utils/connectToWallet.js
• Contract helpers: client/src/utils/contractUtils.js

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AI Helper

The Create Campaign page includes an AI button that augments your inputs to be more compelling. This is served by a Cloudflare Worker (see ai-worker/). If you run your own worker:

1. Deploy with Wrangler to your Cloudflare account.
2. Update the base URL in src/api/aiWorkerInstance.js to point at your worker domain.

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AI Worker API

• Base: your Cloudflare Worker (e.g., https://ai-worker.defund-ai.workers.dev)
• Endpoint: POST /enhance-campaign
• Request (JSON):

{
  "title": "...",
  "description": "...",
  "category": "General",
  "targetEth": 1.5,
  "deadline": "2026-02-28T00:00:00.000Z"
}

• Response (JSON):

{
  "enhancedTitle": "...",
  "enhancedDescription": "..."
}

• Status codes: 200 (OK), 400 (invalid body), 404 (unknown path), 405 (method not allowed), 500/503 (service unavailable/config error)
• CORS: Enabled for POST, OPTIONS with Access-Control-Allow-Origin: *

Source: ai-worker/src/index.js

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AI Worker: Development & Deployment

From the ai-worker directory:

npm install
# Set secret for Groq API key (do not commit secrets)
wrangler secret put GROQ_API_KEY

# Local dev
npm run dev

# Deploy
npm run deploy

Optional local .dev.vars can store non-sensitive dev values. Update the client base URL in client/src/api/aiWorkerInstance.js after deployment if your domain changes.

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Full-Stack Development

Run the worker and client in separate terminals:

# Terminal 1: AI Worker
cd ai-worker
npm install
npm run dev

# Terminal 2: Client
cd client
npm install
npm run dev

Ensure MetaMask is on Sepolia. Set env variables in client/.env before starting.

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Troubleshooting

• MetaMask not installed: Install the extension and refresh the page.
• Wrong network: Switch MetaMask to Sepolia; reconnect wallet.
• Pending request: MetaMask may show -32002; cancel the pending request or wait, then retry.
• User rejected request: Error 4001; re-initiate connect and approve.
• No campaigns visible: Verify VITE_CONTRACT_ADDRESS points to a valid deployed contract.
• AI helper errors: Confirm the worker is running and GROQ_API_KEY is set via Wrangler secrets.

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Data & Services

• CoinGecko (demo): ETH price and conversions. Provide a demo API key in .env.
• Unsplash: Image search and retrieval. Provide a Client ID in .env.

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Best Practices & Notes

• Testnet only: Defund currently targets Sepolia for safe testing — do not use real funds.
• Gas fees: Funding campaigns incurs standard Sepolia gas fees.
• Transparency: All campaign activity (creation, funding) is recorded on-chain.

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Folder Structure (client)

client/
   public/
      logo.png
      demo/
         dashboard.png
         view-campaign.png
         create-campaign.png
         ethereum.png
   src/
      api/
         aiWorkerInstance.js
         unsplashInstance.js
      components/
      contexts/
      utils/
         connectToWallet.js
         contractUtils.js
         getEthPrice.js

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Acknowledgements

• Ethereum & Sepolia testnet community
• CoinGecko API
• Unsplash
• Cloudflare Workers

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Roadmap

• WalletConnect support
• On-chain categories and search
• Campaign updates and milestones
• Multi-currency support and localization

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Disclaimer

This is an educational/testnet project. Always verify contracts and endpoints before use. No guarantees or warranties are provided.