How to Integrate Token Swaps in a Flutter App

Flutter now powers apps used by over 500 million people worldwide, with 2.8 million monthly active developers building across mobile, web, and desktop ( GoodFirms, 2025 ). At the same time, the DeFi market is projected to reach $256.4 billion by 2030, growing at a 43.3% CAGR ( CoinLaw, 2025 ). That intersection creates a clear opportunity: adding token swap functionality to Flutter apps. This guide walks through integrating swapapi.dev into a Flutter application. The API is free, requires no API keys, and supports 46 EVM chains. By the end, you will have a working swap feature that fetches quotes, displays pricing, and submits transactions. What You'll Need Flutter 3.22+ with Dart 3.4+ The http package for API calls The provider package for state management A wallet integration library (e.g., web3dart ) for transaction signing Basic understanding of ERC-20 tokens and blockchain transactions Install the dependencies: dependencies : http : ^1.2.0 provider : ^6.1.0 web3dart : ^2.7.0 json_