Step 3.5 Flash (free)
Model Information
| Slug | step-3-5-flash |
|---|---|
| Aliases |
step-3-5-flash
step35flash
step-3.5-flash
|
| Release Date | February 2, 2026 New |
| AIME 2025 | 0.973 |
| SWE Bench | 0.744 |
| Browse Comp | 0.69 |
Organization
| Name | StepFun |
|---|---|
| Website | https://platform.stepfun.ai |
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.
Available at 11 Providers
| Provider | Model Name | Original Model | Input ($/1M) | Output ($/1M) | Free | Actions | |
|---|---|---|---|---|---|---|---|
|
OpenRouter |
Step 3.5 Flash (free)
|
stepfun/step-3.5-flash
|
$0.00 | $0.00 | ||
|
ZenMUX |
StepFun: Step 3.5 Flash (Free)
|
stepfun/step-3.5-flash-free
|
$0.00 | $0.00 | ||
|
AIHubMix |
step-3.5-flash-free
|
step-3.5-flash-free
|
$0.00 | $0.00 | ||
|
|
ZenMUX |
StepFun: Step 3.5 Flash
|
stepfun/step-3.5-flash
|
$0.10 | $0.30 | ||
|
|
AIHubMix |
step-3.5-flash
|
step-3.5-flash
|
$0.10 | $0.30 | ||
|
302.AI |
step-3.5-flash
|
step-3.5-flash
|
$0.11 | $0.33 | ||
|
Nvidia |
step-3.5-flash
|
stepfun-ai/step-3.5-flash
|
- | - | ||
|
Yupp |
Step 3.5 Flash (OpenRouter)
|
stepfun/step-3.5-flash:free
|
- | - | ||
|
Nano-GPT |
Step 3.5 Flash
|
stepfun-ai/step-3.5-flash
|
- | - | ||
|
|
Nano-GPT |
Step 3.5 Flash Thinking
|
stepfun-ai/step-3.5-flash:thinking
|
- | - | ||
|
StepFun |
step-3.5-flash
|
- | - |