Byzantium Era

First Metropolis hard fork. Added zk-SNARK precompiles, REVERT opcode, and staticcall.

2017-10-16 to 2019-02-28

Blocks 4,370,000 to 7,279,999

5 documented contracts

CryptoCats pre-launch test contract (Nov 2017). The first version to introduce cat names and the allInitialOwnersAssigned() initialization pattern.

Proxy wallet that forwards received ETH to a configured bank address. Owner can sweep ETH and ERC-20 token balances to that same destination.

The first NFT game to achieve mainstream adoption, introducing on-chain collectibles, breeding mechanics, and ERC-721 ownership at global scale.

Exchange deposit wallet (UserWallet). Owner-only ETH collection and ERC-20 token sweeping with Deposit event logging.

An ERC-20 token called FartCoin (FART) deployed in January 2018.