GPT-5.5: OpenAI’s best publicly available model (apr 23, 2026 – 16h 6min, jul 8, 2026 y)
Description:
OpenAI releases GPT-5.5, codenamed "Spud," its most capable model to date and the first full retraining since GPT-5 rather than a post-training layer. The model features a new agent-oriented architecture trained to complete multi-step tasks across tools, with particular strengths in agentic coding, computer use, knowledge work, and early scientific research. At launch, access is limited to Plus, Pro, Business, and Enterprise users in ChatGPT and Codex, with API availability following the next day.Added to timeline:
Date:
apr 23, 2026
16h 6min, jul 8, 2026 y
~ 2 months and 16 days