A DApp developer creates decentralized applications. Decentralized applications are apps that run on a decentralized network, such as a blockchain. A DApp developer builds these apps using programming languages like Solidity or Vyper. They also use frameworks like Truffle or Ganache to help with development and testing. In addition, a DApp developer needs to have a good understanding of cryptography and game theory in order to build secure and successful decentralized applications.