Introducing GPT‑5.4
Simon Willison Blog
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Generative AI
LLMs
Introducing GPT‑5.4 Two new API models: gpt-5.4 and gpt-5.4-pro , also available in ChatGPT and Codex CLI. August 31st 2025 knowledge cutoff, 1 million token context window. Priced slightly higher than the GPT-5.2 family with a bump in price for both models if you go above 272,000 tokens. 5.4 beats coding specialist GPT-5.3-Codex on all of the relevant benchmarks...