Paradex

Paradex is a decentralized cryptocurrency exchange utilizing the 0x protocol for the exchange of ERC20 tokens on the Ethereum blockchain that officially launched in Novermber 2017. On May 23, 2018 Coinbase acquired Paradex. The financial details of the acquisition remain undisclosed.

Paradex is a type of decentralized exchange known as a relayer and uses the 0x protocol "Matching Model". Paradex maintains an off-blockchain order book of the limit buy (takers) and sell orders (makers) made by traders. Compared to decentralized exchanges where all orders are placed on the blockchain, this method reduces the cost and time delay associated with placing every potential order (including unfilled and cancelled orders) on the blockchain.

Once orders are matched the transaction is completed on-chain using the 0x protocol. Paradex actually acts as the trade partner with both maker and taker simultaneously, acting as a relay between the matching orders. ERC-20 tokens are not continuously held in a large exchange wallet, thus reducing the risk of a hack stealing a large number of users funds held within a single exchange wallet.

Paradex charges a trading fee of 0.15% on each side of the trader. The Ethereum Gas cost is passed to the user in the form of a transaction cost.