A few months ago the 0x team announced the launch of the 0x v3 exchange contracts. The highlights of this upgrade are:

The OpenRelay team is happy to announce that we have deployed support for 0x v3.

Change of Testnets

The first thing to note is that OpenRelay is dropping support for the Kovan testnet with the move to 0x v3, and replacing it with the Rinkeby testnet.

Kovan is the only major Ethereum testnet that is not supported by multiple clients, and Parity (the only client that does support it) has an uncertain future ahead. We have elected to support Rinkeby, which is a proof-of-authority testnet supported by most Ethereum clients.


OpenRelay has historically used a flat, flexible fee structure in ZRX. We would set our base fee in ZRX, and accept any order where the maker fee + the taker fee was at least that base fee. As the price of ZRX fluctuated we would adjust the required amount of ZRX to keep the fee fairly constant in dollar terms.

0x v3 introduces flexibility for fee tokens — the token for the fees is specified on each order, rather than by the protocol.

For us, this lead to a bunch of questions for what fees look like in our future. Do we keep our flat flexible fee structure? Do we accept fees as a percentage of the tokens being traded? It leaves us with a lot of options.

For our initial launch of v3 support, we decided to stick with something very similar to our historic model. We’ve shifted from taking fees in ZRX to taking fees in DAI, so that we won’t have to adjust fees periodically. We will be charging 0.50 DAI per order, which can be paid by the Maker, the Taker, or a combination thereof.

If you operate a pool an OpenRelay, you’re free to set fees in any ERC20 token you like.

Limitations on Aggregated Liquidity

A big feature of 0x v3 is the ability to aggregate liquidity from a wide range of on-chain liquidity sources. OpenRelay does not directly support these orders, but you can use 0x API for that liquidity alongside orders from OpenRelay.

0x V2 Deprecation Timeline

We will continue to support our 0x v2 endpoints through April 17, 2020. On April 18, if there are any orders remaining on the v2 orderbook we will put the orderbook into read-only mode until April 30 to allow orders to be used. On April 30 we will take v2 endpoint offline. If the orderbook is cleared of orders between April 18 and April 30, we may take v2 offline early.