Clients working with a Next.js developer can anticipate a set of customized deliverables tailored to their specific web application project. These typically encompass the fully functional web application, access to the application's source code, reusable design components, detailed technical documentation, and insights into testing, deployment, and ongoing maintenance. Clear communication and well-defined project agreements are pivotal to ensuring that the client's expectations are met and that the project aligns with their unique requirements and goals.