StepFun: Step 3.5 Flash (free)
Analysis Summary
StepFun: Step 3.5 Flash (free) sits in the Legacy tier on our leaderboard, ranked #545 of 561 published models on overall intelligence. At $0.000 input and $0.000 output per 1M tokens, it is among the most expensive on the market. It offers a generous context window for extended reasoning and code review and supports tool use and function calling.
Editorial notes
Free tier of Step 3.5 Flash with tool use and a 256K context window, but no benchmark data available to verify capability for business workflows.
Assessed May 14, 2026
Rankings consider pricing, capabilities, benchmarks, and real-world applicability and are refreshed as new models launch. Feedback?
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
How does StepFun: Step 3.5 Flash (free) stack up?
Compare side-by-side with other legacy 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 |
