Codex gets smarter with GPT-5, targets GitHub Copilot and rivals

OpenAI has enhanced its GPT-5 model specifically for Codex, the company's agentic software development tool, with CEO Sam Altman revealing that Codex now generates 40% of platform traffic.

The upgraded GPT-5 Codex offers comprehensive development capabilities, including building complete projects, adding features, running tests, refactoring large codebases, and conducting detailed code reviews. The model dynamically adjusts processing time based on task complexity and can operate autonomously for over seven hours, handling refactoring and bug fixes while delivering finished code. Early testing shows improved reliability in catching critical bugs, enabling developers to concentrate on high-priority issues.

• Can run independently for 7+ hours completing complex development tasks
• Dynamically adjusts processing time based on project complexity requirements
• Available across multiple platforms including terminal, IDE integrations, and GitHub
• Aims to compete directly with GitHub Copilot, Google Gemini, and Anthropic Claude