Ethereum apps are typically written in Solidity before being compiled to EVM bytecode. The EVM bytecode must be public, but one could keep the (more readable) S

Ethereum apps are typically written in Solidity before being compiled to EVM bytecode. The EVM bytecode must be public, but one could keep the (more readable) Solidity code private, like distributing an executable without the source. I think it would be unusual though.