OpenAI launched GPT-5.4 in Thinking and Pro variants, reporting 57.7% on SWE-bench Pro, around 80% on SWE-bench Verified, and 75% on OSWorld for computer use — with a 1M-token context window and 128K max output.

Smaller GPT-5.4 mini and nano variants followed on March 17 for faster, lower-cost workloads, going GA across all Copilot tiers the same day.

GPT-5.4-class models were pulled from Codex at the end of August 2026 as the GPT-6 generation took over the flagship slot.