StepFun

StepFun is a leading Chinese AI large model company with its Step series of multimodal large models. The latest Step 3 uses a MoE architecture with 321B total parameters and 38B activated parameters, was officially open-sourced in July 2025, and reaches industry-leading levels on multiple benchmarks.

Core Capabilities

• Multimodal Reasoning: Strong visual perception and complex reasoning, with a 5B Vision Encoder
• Efficient Inference: MFA attention mechanism achieving 4039 token/gpu/s on Hopper GPUs
• Web Search: Online search for real-time information
• Image Generation: Text-to-image capability
• Knowledge Base Q&A: Supports custom knowledge bases

Use Cases Intelligent conversation, content creation, code generation, and document analysis. Developers can integrate via API, while ordinary users can use it directly through the web and app.

Unique Advantages Step 3 performs excellently on benchmarks including MMMU, MathVision, and AIME 2025, with inference efficiency significantly higher than DeepSeek V3. As an open-source model, it offers a high degree of technical transparency.

Editor's Recommendation A standout among Chinese large models — open-sourcing Step 3 demonstrates real technical strength. API pricing is competitive, well suited to cost-sensitive developers.