7 Best Crypto APIs for Next.js and React DeFi Apps

Building a DeFi frontend in React or Next.js means stitching together multiple APIs for swaps, prices, wallet data, and more. The DeFi ecosystem now holds over $180 billion in total value locked, and on-chain DEX trading volumes regularly exceed $10 billion per day. Meanwhile, Next.js powers over 25% of the top 10,000 websites and has become the default framework for crypto frontends thanks to its SSR, API routes, and edge runtime support. React-based frameworks dominate Web3 frontend development, with over 78% of DeFi dashboards and wallet interfaces built on React. This guide covers the 7 APIs you actually need to build a production DeFi app in Next.js or React — from token swaps to NFT data — with TypeScript examples you can drop into your codebase today. 1. Swap API (swapapi.dev) — Token Swaps Swap API is a free DEX aggregator that returns executable swap calldata from a single GET request. It covers 46 EVM chains, requires no API key, no registration, and no account. CORS headers