SStepFun · Released Jan 29, 2026
Step 3.5 Flash
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....
- Released
- Jan 29 2026
- Context window
- 262K 66K out
- Input / 1M tokens
- $0.10
- Output / 1M tokens
- $0.30
Where to run it
Providers
Only SiliconFlow serves Step 3.5 Flash on OpenRouter right now.
| Provider | Input | Output | Context | Max output | Uptime | vs. best |
|---|---|---|---|---|---|---|
| SiliconFlowFP8 | $0.10 | $0.30 | 262K | 66K | 99.1%24h | Cheapest |
Benchmarks
Benchmark scores
No benchmark scores yet — Epoch AI hasn't evaluated Step 3.5 Flash. Scores appear here automatically once it does.
Specs
Details
- Model ID
stepfun/step-3.5-flash- Developer
- StepFun
- Release date
- Jan 29, 2026 ·
- Context window
- 262,144 tokens
- Max output
- 65,536 tokens
- API price
- $0.10 / $0.30 per 1M input / output tokens
- Providers
- 1
- Input types
- text
- Reasoning
- Yes
- Tool calling
- Yes
- Open weights
- Yes
- Free tier
- No
Release date, prices and providers from OpenRouter's catalog; buying directly from a provider can cost a little differently. Uptime is the share of OpenRouter requests each provider served over the last day. Benchmark scores are the best result per benchmark from Epoch AI, licensed CC BY 4.0. Rank counts every model tracked here with a score.