GPT-5 Nano reasoning

openrouter
openai
GPT-5-Nano is the smallest and fastest variant in the GPT-5 system, optimized for developer tools, rapid interactions, and ultra-low latency environments. While limited in reasoning depth compared to its larger counterparts, it retains key instruction-following and safety features. It is the successor to GPT-4.1-nano and offers a lightweight option for cost-sensitive or real-time applications.

Capabilities

Context Window 400k tokens
Max Output 128k tokens
Inputs
Outputs

Pricing (per 1M tokens)

Input $0.05
Output $0.40
Cache Read $0.01
Cache Write -

Supported Parameters

include_reasoningmax_tokensreasoningresponse_formatseedstructured_outputstool_choicetools

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