We have completed architecture design for integration with 0x, which will allow for decentralised settlement of trades.

Ethfinex will distribute APIs and open-source smart contract tools through which to integrate & interface with other projects and exchange protocols throughout the Ethereum ecosystem. Planned integrations currently include the likes of Melonport, 0x, Blocknet and more.
Further integration throughout the Ethereum ecosystem is planned, including the development of Ethereum-based fiat tokens with Tether.to, and these relationships will be announced when the integration details are fixed.