DeepSeek V3 Base and GPT-5 nano don't publish scores on any of the same benchmarks, so there's no direct head-to-head comparison. DeepSeek V3 Base shipped 249 days before GPT-5 nano, so benchmark comparisons should account for the intervening progress.

DeepSeek V3 Base is open weight, while GPT-5 nano is proprietary.

Direct benchmark comparisons are unavailable — DeepSeek V3 Base and GPT-5 nano don't publish scores on any of the same benchmarks.