Etheno is the Ethereum testing Swiss Army knife. It’s a JSON RPC multiplexer, analysis tool wrapper, and test integration tool. It eliminates the complexity of setting up analysis tools like Manticore and Echidna on large, multi-contract projects. In particular, custom Manticore analysis scripts require less code, are simpler to write, and integrate with Truffle. If you are a smart contract developer, you should use Etheno to test your contracts. If you are an Ethereum client developer, you should use Etheno to perform differential testing on your implementation. For example, Etheno is capable of automatically reproducing the Constantinople gas usage consensus bug that caused a fork on Ropsten.