How to Build an Arbitrage Bot with a Swap API

Crypto arbitrage bots generated over $500 million in extracted value on Ethereum alone in 2024, and DEX trading volume across EVM chains exceeded $1.76 trillion that same year. The opportunity is real, but most tutorials drown you in smart contract ABIs, router addresses, and multi-library setups before you can even fetch a price. This guide takes a different approach: you will build an arbitrage bot using a single GET request to a swap API, skipping all the contract-level complexity. By the end, you will have a working bot that monitors price differences across chains and tokens, calculates profitability including gas costs, and executes swaps on-chain. No API keys, no SDKs, no accounts required. What You'll Need Node.js 18+ or Bun (examples use Bun for speed) A wallet with a private key funded on your target chains ethers.js v6 (npm install ethers) Basic HTTP knowledge — the entire swap integration is one GET request The bot uses swapapi.dev, a free DEX aggregator API covering 46 EVM