StepFun: Step 3.5 Flash (free)
Analysis Summary
StepFun: Step 3.5 Flash (free) sits in the Legacy tier on our leaderboard, ranked #527 of 544 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
StepFun Step 3.5 Flash free tier offers tool use and function calling with a 256K context at no cost, but lacks benchmark data to confirm the performance level of the paid version.
Assessed May 5, 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 |
