StepFun: Step 3.5 Flash
StepFun: Step 3.5 Flash is designed to handle text-based inputs with an impressive context length of 262,144 tokens and can generate up to 65,536 completion tokens. It supports tools and reasoning capabilities, making it versatile for complex tasks. While it doesn't offer structured output or open-source weights, its blend score of 42.9 across independent benchmarks places it competitively. Given its pricing at $0.1 per million input tokens and $0.3 per million output tokens, StepFun: Step 3.5 Flash is suitable for projects with a budget-conscious approach but still requiring robust text processing capabilities. Its benchmark score suggests it performs well in various contexts, making it a strong choice for those looking to balance cost and performance effectively.
Benchmark results
Independent, published benchmarks. Blended score 42.9 across 1 benchmark, last refreshed 2026-08-13. How scoring works →
| Benchmark | Measures | Score |
|---|---|---|
| AI Index | broad capability composite | 43.8 |
- Model ID
- stepfun/step-3.5-flash
- Vendor
- stepfun
- Released
- January 2026
- Tokenizer
- Other
- Input Modalities
- text
- Output Modalities
- text
- Max Output
- 65,536 tokens
- Tool Calling
- ✓ supported
- Structured Output
- not supported
- Reasoning Mode
- ✓ supported
- Vision
- text only
- Audio
- no
- Moderated
- no
What it costs in practice
Computed from the current $0.10/M input and $0.30/M output rates. Run your own numbers →
| Job | Tokens | Cost |
|---|---|---|
| Summarize a 50-page report | 30k in / 1.5k out | under $0.01 |
| Classify 1,000 customer emails | 500k in / 50k out | $0.07 |
| A month of a busy support chatbot | 5M in / 2M out | $1.10 |
Similar models
Quick answers
- How much does StepFun: Step 3.5 Flash cost?
- $0.10 per million input tokens and $0.30 per million output tokens.
- What is StepFun: Step 3.5 Flash's context window?
- 262,144 tokens, roughly 393 pages of text in a single request.
- Does StepFun: Step 3.5 Flash support tool calling?
- It supports tool calling, a reasoning mode.
- Can StepFun: Step 3.5 Flash process images?
- No, it is text-only on the input side.