Step 2

Step 2, launched by Shanghai startup StepFun at WAIC in July 2024, was the first trillion-parameter mixture-of-experts model built by a Chinese company. The Step-2-16k variant topped Chinese LLM rankings and reached 5th worldwide on LiveBench, with standout instruction-following (86.57) and solid reasoning — a milestone moment for China's 'AI tigers' cohort founded by ex-Microsoft researcher Jiang Daxin.

The model is served through StepFun's API platform and powers the consumer Yuewen assistant app. StepFun later open-sourced other models (Step-Video-T2V, Step-Audio, Step 3.5 Flash under Apache 2.0), but Step 2 itself stayed closed-weights and API-only.

Honest caveats: it is a 2024 model whose coding and math scores lagged even then, documentation in English is thin, and availability outside China is limited. Later Step 3 and Step 5 generations moved the lineup forward. Historically, though, Step 2 marks the moment a Chinese startup joined the trillion-parameter club.