6 Best Ethereum Swap APIs for DeFi Developers

Ethereum still holds over $68 billion in DeFi TVL and processes roughly $1.28 billion in daily DEX volume as of Q1 2026. If you are building a wallet, trading bot, or DeFi dashboard, you need an Ethereum swap API that returns executable calldata, handles slippage, and lets you ship without waiting for API key approvals. Swap fees on mainnet have dropped to $0.39 per swap on average after the Dencun upgrade cut gas costs by 95%, making programmatic trading on L1 more viable than ever. This guide