StepFun · Released Jan 29, 2026Step 3.5 Flash
StepFun flash lane for quick multimodal reasoning and coding assistance.
- Capability
- —No ECI score yet
- Input
- $0.10per 1M tokens
- Output
- $0.30per 1M tokens
- Context
- 256K256K max output
What it costs
- Input
- $0.10per million tokens
- Output
- $0.30per million tokens
- Cached input
- $0.02per million tokens
- Blended (3:1)
- $0.15cheaper than 83% of priced models
Typical monthly bills
| Monthly usage | Estimated cost |
|---|---|
| Side project2M input + 0.5M output tokens | $0.35 |
| Team assistant25M input + 5M output tokens | $4.00 |
| Production app250M input + 50M output tokens | $40.00 |
Official StepFun (Global) API price, as listed on models.dev.
Independent benchmarks
Epoch AI has not published a Capabilities Index score for Step 3.5 Flash yet.
The details
- Lab
- StepFun
- Released
- Jan 29, 2026
- Knowledge cutoff
- Jan 2025
- Context window
- 256,000 tokens
- Max output
- 256,000 tokens
- Inputs
- Text
- Output
- Text
- Reasoning
- Adjustable effort low · high
- Tool calling
- Yes
- Structured output
- No
- Weights
- Open weights
- API model ID
step-3.5-flashon StepFun (Global)- Availability
- 8 API providerslisted on models.dev
What StepFun claims
Published by the lab at launch. Settings vary, so compare these only with care.
More from StepFun
About Step 3.5 Flash
How much does Step 3.5 Flash cost?
Step 3.5 Flash costs $0.10 input / $0.30 output per million tokens (official StepFun (Global) API price). Cached input is $0.02 per million tokens. At a 3:1 input-to-output mix that is $0.15 per million tokens, cheaper than 83% of the 360 priced models we track.
What is the context window of Step 3.5 Flash?
Step 3.5 Flash accepts up to 256,000 tokens per request and can write up to 256,000 tokens in one response.
How good is Step 3.5 Flash?
Epoch AI has not published a Capabilities Index score for Step 3.5 Flash yet.
Is Step 3.5 Flash open source?
Yes. StepFun publishes the weights, so it can be downloaded and self-hosted.
What inputs does Step 3.5 Flash support?
Step 3.5 Flash accepts text and replies in text. It is a reasoning model with low and high effort settings, supports tool calling.
When was Step 3.5 Flash released?
StepFun released Step 3.5 Flash on Jan 29, 2026. Its training data runs to Jan 2025.
What are the best alternatives to Step 3.5 Flash?
The closest current models from other labs on capability, price and release date are GLM-4.7-FlashX (Z.ai (Zhipu), $0.07 / $0.40), Devstral Small 2 (Mistral AI, $0.10 / $0.30), Seed 2.0 Lite (ByteDance Seed, $0.089 / $0.534) and Trendyol Asure 12B (Trendyol, $0.10 / $0.50).