StepFun opens Step 5 Preview API: 600B MoE at $1/$2.70 per M tokens
StepFun opened API access to Step 5 Preview on Sept 20: a proprietary 600B sparse MoE (27B active) with a 1M-token context, vision input, and Artificial Analysis pricing of $1/$2.70 per million tokens (Intelligence Index 44). Company-reported coding scores still trail GPT-6 Astra and Claude Opus 5 on several benches; open weights are planned for Oct 15.