StepFun: Step 3.5 Flash (free)
Review
StepFun's Step 3.5 Flash free tier offers tool use and function calling at no cost, but without its own benchmark data this variant cannot be reliably scored — the paid version's benchmarks suggest reasonable mid-tier capability.
Assessment date: April 16, 2026
Our methodology takes into account a range of factors including pricing, functionality, capabilities, benchmark performance, and real-world applicability. Rankings are reviewed and updated regularly as new models are released. Issues with our rankings? Contact us
Performance Profile
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..
Capabilities
Architecture
| Modality | Text → Text |
| Tokenizer | Other |
How does StepFun: Step 3.5 Flash (free) stack up?
Compare side-by-side with other emerging models.
Model Information
| OpenRouter ID |
stepfun/step-3.5-flash:free
|
| Provider | stepfun |
| Release Date | January 29, 2026 |
| Context Length | 256,000 tokens |
| Max Completion | 256,000 tokens |
| Status | Active |
