Express Protocol is an open-source TypeScript SDK for building onchain NFT and real-world-asset applications, including minting, trading, and agent payments without writing Solidity.
Express Protocol provides typed SDK interfaces over audited smart contracts for ERC-721, ERC-1155, ERC-404, and x402 USDC agent payments. It supports minting and collections, royalties, fixed-price sales, auctions, IPFS/Pinata metadata storage, and multichain NFT data, with support for viem/web3 signers, ERC-4337 account abstraction, and deployment on Base, Arbitrum, and Optimism.