GPT-5 Nano is OpenAI's fastest and most cost-efficient model in the GPT-5 family, optimized for high-throughput applications requiring minimal latency. With pricing at just $0.05 per million input tokens, it excels at straightforward tasks like classification, summarization, and simple question-answering. While its reasoning capabilities are more limited than larger variants, it maintains strong instruction following and delivers exceptional speed, making it ideal for real-time applications and cost-sensitive deployments at scale.