Step 5 Preview Tops OpenRouter Trending Ahead of October 15 Open-Source Release

What happened

StepFun's flagship base model Step 5 Preview reached the top of OpenRouter's Trending list and second place on its daily ranking, with an official open-source release set for October 15. The sparse MoE model has 600 billion total parameters and about 27 billion activated per token, and Artificial Analysis gives it a composite intelligence index of 44, placing it in the global open-source top three.

The story so far

StepFun has launched Step 5 Preview, and Tencent has integrated it into WorkBuddy with two weeks of free access starting October 12; its official open-source release is scheduled for October 15. Leiphone reported that the model also reached first place on OpenRouter’s Trending list and second place on its daily ranking. Step 5 Preview uses a sparse mixture-of-experts architecture with 600 billion total parameters and about 27 billion activated per token. Leiphone’s initial report placed its Artificial Analysis Intelligence Index score of 44 in the global open-source top two, while its later report gave the same score but placed it in the top three. The WorkBuddy offering is intended to support deep research, information retrieval, data analysis, document and presentation generation, and complex, multistep tasks. The two-week free-access offer applies specifically to Step 5 Preview within WorkBuddy.

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