Yes, the current version of OpenAI Codex is designed specifically to write complete programs and handle entire software development tasks. Unlike the original 2021 version that focused mainly on code completion and snippet generation, the 2025 Codex is an autonomous software engineering agent capable of building full applications from scratch. When given a high-level description of what you want to build, Codex can create entire projects with multiple files, proper project structure, dependencies, configuration files, and even tests. It understands how to organize code into logical modules and follows software engineering best practices throughout the development process.
The system approaches complete program development by breaking down complex requirements into manageable tasks and implementing them systematically. Codex can set up development environments, install necessary dependencies, create appropriate file structures, and implement features across multiple files while maintaining consistency and proper integration between components. It understands concepts like separation of concerns, code reusability, and maintainable architecture. For web applications, it can create both frontend and backend components, set up databases, handle user authentication, and implement complete user flows from start to finish.
What makes Codex particularly effective at writing complete programs is its ability to iterate and refine its work. The system can run tests, identify issues, and fix problems until the program works correctly. It can also respond to feedback and requirements changes, modifying existing code while maintaining the overall architecture and functionality. The agent works in isolated sandbox environments where it can safely execute code, test functionality, and verify that everything works as expected before presenting the final result. This iterative approach ensures that the complete programs it generates are not just syntactically correct but actually functional and ready for real-world use.