GPT-5.5 is OpenAI's first fully retrained base model since GPT-4.5, codenamed "Spud" and released April 23, 2026 as a successor to GPT-5.4. Purpose-built for agentic workflows, it can understand complex goals, use tools, verify its own work, and carry multi-step tasks to completion with minimal human direction. OpenAI describes it as a faster, sharper thinker for fewer tokens than GPT-5.4, excelling at data analysis, coding and debugging, operating software, web research, and producing documents and spreadsheets. At launch it scored 82.7% on Terminal-Bench 2.0, 84.9% on GDPval, and 78.7% on OSWorld-Verified, outperforming Claude Opus 4.7 and Gemini 3.1 Pro on several key agentic benchmarks. It rolls out first to Plus, Pro, Business, and Enterprise tiers in ChatGPT and Codex, with API availability following shortly under additional safeguards.
