Update: Step 5 Preview's API is live at $1/$2.70 per million
StepFun opened access the day it announced: 600B params / 27B active, 1M context, a 95% cache-read discount, and open weights promised for Oct 15.
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You can run it today — no waitlist
StepFun opened Step 5 Preview's API the same day it announced the model on Sept 20. Pricing is $1 per million input tokens and $2.70 output, with a 95% cache-read discount that cuts cost hard for agents and long-context jobs that re-read the same prompt.
Kimi K3 Max scores at a seventh of GPT-5.6's price
It posts 44 on Artificial Analysis's Intelligence Index — level with Kimi K3 Max — while costing roughly one-seventh of GPT-5.6 Sol. Under the hood it's a 600B sparse MoE with 27B active per token and a 1M-token context window.
Open weights land Oct 15 — the repo's still empty
StepFun says it'll release open weights on Oct 15, but the Hugging Face repo currently holds only a .gitattributes file. If you'd rather self-host than hit the API, mark the date — there's nothing to download yet.