GPT-5.4 unifies reasoning and coding in one model with 1M-token context.
OpenAI's GPT-5.4 combines frontier coding from GPT-5.3-Codex with advanced reasoning into a single model, rolling out to ChatGPT Plus, Team, and Pro users. It introduces a 1M-token experimental context window and a fast mode delivering up to 1.5x faster token output.
openai.com/index/introducing-gpt-5-4