OpenAI releases GPT-5.5, its most advanced coding AI model, now available in Codex developer tools

OpenAI shipped GPT-5.5 as the default model in Codex v0.122.0, replacing GPT-5.4 as the latest 'frontier agentic coding model' — an AI trained specifically to write, debug, and refactor code without step-by-step human instruction.

GPT-5.5 is positioned as an agent (an AI that makes decisions and takes actions on its own rather than just suggesting completions), meaning it can attempt multi-step coding tasks, detect its own mistakes, and fix them — compressing hours of manual code review and revision into seconds.

For software developers and engineering teams, this means faster code completion, fewer bugs caught before production, and reduced time spent on routine refactoring work — making it easier to ship features quickly, especially for teams with tight deadlines or limited engineering capacity.