Xchangeo

Xchangeo is a fully decentralized, EVM-compatible exchange built on the Automated Market Maker (AMM) model. It provides a seamless platform for ERC20 token swaps, liquidity provisioning, slippage protection and fee mechanism and real-time analytics powered by an on-chain indexer. This project demonstrates a complete end-to-end dApp architecture, from smart contracts to a modern, reactive frontend.

This project is modeled with a constant product market maker logic and designed to be fully EVM-compatible. It includes custom token faucets, an indexer built with The Graph, and a modern frontend for liquidity control and token tracking.

Live Application

Check out the live deployment: https://xchangeo.vercel.app/

Table of Contents

• Features
• Tech Stack
• Smart Contracts
• Indexer
• Contributing
• Reach me out

Features

• ⚖️ Decentralized ERC20 Swaps: Swap supported ERC20 tokens directly on-chain using the constant product formula ($x * y = k$).

• 💧 Liquidity Pools & LP Tokens: Add or remove liquidity to token pairs and receive LP (Liquidity Provider) tokens representing your share of the pool.

• 🛡️ Slippage & Fee Handling: Smart contract-enforced slippage protection and a transparent fee mechanism ensure fair and predictable trades.

• 📈 Real-time Pool Analytics: View pool performance with interactive, real-time charts for price movements, liquidity, and protocol fees via an integrated Subgraph indexer, ensuring accurate insights into trading activity and LP positions.

• 🧩 Modular & Battle-tested Contracts: A clean, modular contract architecture separating the factory, pools, and routing logic.

• 🧪 Token Faucets: Includes custom faucets to acquire test tokens for experimenting with the platform.

• 🌐 Full Local Development Stack: A Docker-based environment that replicates the entire production stack (Hardhat Node, Indexer, Frontend) for seamless offline development and testing.

Tech Stack

• Frontend: Next.js, Server-Side fetching, Tailwind CSS, TypeScript, React Hook Form & Zod Validation, Reown Wallet Kit, Ethers.js etc
• Backend: Hardhat, Solidity (Smart Contracts)
• Indexer: TheGraph, GraphQL, Docker
• Testing: Thorough testing using Chai, TypeScript and Ethers.js for robust smart contract.
• Blockchain: Sepolia Testnet (Ethereum)
• Tools: Hardhat, Ethers.js

Smart Contracts

The smart contracts for Xchangeo are written in Solidity and implement the core protocol logic, including token swaps, liquidity provisioning, LP token minting/burning, and fee distribution. Additional contracts support custom token faucets for testing. All contracts are deployed on the Sepolia Testnet, an Ethereum-compatible network.

Here is the list of all contracts deployed on the Sepolia testnet:

{
  "ERC20Token_DAI": "0x4854F674F5c26FF24Bda3F231177368B45C46aB3",
  "ERC20Token_LINK": "0x50E0F593305f2ba31AfB5F17De6C61390CaD2e4c",
  "ERC20Token_USDC": "0x5C7c5D30402c6f1AA21eC81c8E3CbFe50C38c6B8",
  "ERC20Token_USDT": "0x298858DDcFa8C475d6580b5D2Fcc4d8365A31Fb5",
  "ERC20Token_WBTC": "0xeDcFf9982C22f64Afe248b8BD088Fc3c9863A8e3",
  "ERC20Token_WETH": "0x37af3A601301F858F8C1E89426459714eE8B69fe",
  "Faucet_DAI": "0x42dA0Dee05ABE99F11C73d9E1dfC7b43130C35e1",
  "Faucet_LINK": "0x99B8b358A1098529c11dc148621b39dDc0168Cc5",
  "Faucet_USDC": "0x34e74cE0c019C80643Afaa403f51C92D48A98Ca3",
  "Faucet_USDT": "0x306E3bEbe6D82850178269A48B220cbbFCd93311",
  "Faucet_WBTC": "0x57911E20A857C28E082f30145bBcb1659Fdc7f1F",
  "Faucet_WETH": "0x71CaC24D3FfC2987CEFFa2B1e130DEa3D3B913F0",
  "Pool_LINK_WETH": "0x877303A3a0F7d4ce6307834a34168DcC41642afD",
  "Pool_USDC_DAI": "0xA391760a43672061297D326F7703223145240989",
  "Pool_USDT_USDC": "0x27418f3BaC291d24Fd7Cb252906F20f5Fc006Fd9",
  "Pool_USDT_WBTC": "0x55FEB15bB7a5e84733C905f6878f96e5e4274995",
  "Pool_WETH_USDC": "0xf6F61B54B7bbe655cEAC5Dc6c161AF0d3B5B1C17",
  "Pool_WETH_WBTC": "0x73676BE2e60aE2600D6F97699Cb0CD6B557E8579"
}

Indexer

Xchangeo uses The Graph to index key events and state changes on-chain:

• Token swaps
• Liquidity added/removed
• LP token supply changes
• Token reserves and pool states
• and much more

The indexed data can be queried through a GraphQL API used by the frontend for real-time updates.

Contributing

Contributions are welcome! Please fork the repository and submit a pull request.

1. Fork the repository
2. Create a new branch (git checkout -b feature-branch)
3. Commit your changes (git commit -m 'Add some feature')
4. Push to the branch (git push origin feature-branch)
5. Open a pull request

Local Development Setup

Follow these steps to set up and run the entire project on your local machine.

Prerequisites

• Node.js (v18 or later)
• pnpm
• Docker and Docker Compose

1. Clone the Repository

git clone https://github.com/ap211unitech/xchangeo
cd xchangeo

2. Install Dependencies

Install dependencies for all workspaces (root, client, hardhat).

3. Configure Environment Variables

The client application requires environment variables. Create a .env.local file inside the /client directory.

NEXT_PUBLIC_REOWN_PROJECT_ID=
NEXT_PUBLIC_GRAPHQL_API_ENDPOINT=
NEXT_PUBLIC_RPC_URL=

4. Run the Local Stack

cd hardhat
npx hardhat test # run all unit and integration tests
npx hardhat compile # compiles all Solidity contracts and generates artifacts (ABI, bytecode, metadata)
npx hardhat node # keep this running
npx hardhat ignition deploy ./ignition/modules/index.ts --network localhost # add `--verify` to verify contracts

cd indexer
pnpm clean
pnpm ready
pnpm docker:start # keep this running
pnpm create-local && pnpm deploy-local

cd client
pnpm dev

You should now have:

The frontend running at http://localhost:3000

The local Hardhat node at http://localhost:8545

The indexer's GraphQL endpoint at http://localhost:8000/subgraphs/name/indexer

Reach me out

Arjun Porwal - [email protected]

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