How to Build a Multi-Chain Swap Interface

Building a multi-chain swap interface used to mean integrating separate SDKs for each DEX on each chain, managing router contract addresses, and handling incompatible ABIs across networks. With over $5 billion in daily DEX volume spread across Ethereum, Arbitrum, Base, Polygon, BSC, and dozens of other EVM chains, users expect a single UI that lets them swap tokens on any network without switching apps. This guide walks you through building a production-ready multi-chain swap interface using React, wagmi/viem, and a single swap API that covers 46 EVM chains. By the end, you will have a working frontend that handles chain selection, token input, real-time quoting, and on-chain execution — all powered by one GET endpoint. What You'll Need Node.js 18+ and a package manager (npm, pnpm, or bun) React 18+ with TypeScript (Next.js or Vite) wagmi v2 and viem for wallet connection and transaction submission A swap API — this guide uses swapapi.dev, which is free, requires no API key, supports 4