Opyn, a European DeFi options trading protocol, enables users to buy, sell, and create Ethereum-based options.  Options are derivatives contracts that give the owner (buyer) the right to buy or sell an asset at a specific price at the option expiration date. DeFi users rely on Opyn's smart contracts and interface to hedge against risks or to speculate on cryptocurrencies. Opyn provides free limit orders to its users by utilizing 0x's unique off-chain relay and on-chain settlement architecture.