GPT-5.5

GPT-5.5, released April 23, 2026 with API access following the next day, pushed the context window to roughly 1 million tokens and lands meaningfully above GPT-5.4 on long-context recall, multi-step tool use, and code generation in large repositories, though it costs more per token. Standard pricing is $5 per million input tokens and $30 per million output tokens, with GPT-5.5 Pro available at $30/$180 for the hardest problems, and OpenAI offers batch and flex pricing at half the standard rate alongside a 2.5 times priority tier for latency-sensitive use. It topped the ARC-AGI-2 leaderboard at roughly 85 percent, the highest score any model had reached on that benchmark at the time, and OpenAI replaced it with GPT-5.6 less than three months later.