StepFun

StepFun is a Chinese AI startup founded in 2023, focused on large-model R&D. It released the Step series of 100-billion-parameter LLMs, focusing on multimodal understanding and generation. It launched the consumer assistant Yuewen, making it one of the representative Chinese LLM startups.

AI Tools

JieYueXingChen

From coding to agents: self-developed models, multimodal AI, open API & Studio

StepFun

Intelligent AI assistant that delivers answers, inspiration, and efficiency

AI Models

Step 5 Preview

StepFun

Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters). It performs strongly in software engineering and professional knowledge work, with particular strength in finance. It is designed for extended tasks that span large codebases and documents, using tools and refining results over multiple steps.

Context: 1M
Max output: -
Released: 2026-10-08

Input: $1 /M
Output: $2.7 /M

Step 3.7 Flash

StepFun

Step 3.7 Flash is StepFun's latest high-efficiency multimodal Mixture-of-Experts model. It pairs a 196B-parameter language backbone with a vision encoder for native image and video understanding, activating roughly 11B parameters per token. The model supports a 256K context window and exposes selectable reasoning levels (high/medium/low), letting callers trade off speed, cost, and depth of reasoning. Designed for coding, agentic workflows, structured outputs, and long-context productivity tasks.

Context: 262.1K
Max output: -
Released: 2026-05-28

Input: $0.2 /M
Output: $1.15 /M

Step 3.5 Flash

StepFun

Step 3.5 Flash is StepFun's most capable open-source foundation model. Built on a sparse Mixture of Experts (MoE) architecture, it selectively activates only 11B of its 196B parameters per token. It is a reasoning model that is incredibly speed efficient even at long contexts.

AI Tools

JieYueXingChen

StepFun

AI Models

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