API pricing for the latest Mixture-of-Experts system is $1.00 per 1 million input tokens and $2.70 per 1 million output tokens. This latest offering from the Chinese AI developer, named Step 5 Preview, uses 27 billion active parameters per token and a 1 million token context window. It is available now via StepFun AI Studio and the Step Plan subscription, providing vision capabilities and specialized proficiency in finance and software engineering.

The model matches Kimi K3 (max) with a score of 44 on the Artificial Analysis intelligence index but operates at approximately 65% lower cost per task. In coding benchmarks, Step 5 Preview scored 33% on Terminal-Bench 4.0, surpassing the 27% recorded by DeepSeek V4.1 Flash, and reached 59% on SciCode. StepFun will release the weights for the 600B parameter model on Oct 15.

Early evaluations from Zhihu contributors indicate uneven performance, with strengths in scientific coding offset by gaps in factual knowledge and complex document handling. This version is positioned for agentic work and sustained execution over long horizons. StepFun developed the model to advance the cost-intelligence Pareto frontier by reducing costs for professional knowledge work.