Step 3.5 Flash
step-3.5-flashStep 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.... Built by StepFun.
Prices updated
Input price
$0.10
per 1M tokens · Standard
Output price
$0.30
per 1M tokens · Standard
Input limit
262K
tokens
Output limit
66K
tokens
Input formats
Output formats
Step 3.5 Flash price history
2 price records since 10/8/2026
Step 3.5 Flash cost calculator
$3.50/month
Standard pricing
Overview
What is Step 3.5 Flash?
Step 3.5 Flash is a text & reasoning model from StepFun. 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.... Its 262K context window and $0.10 input price make it a candidate for cost-sensitive, high-throughput applications.
Rates
Step 3.5 Flash pricing
Pricing is based on token usage. Provider-specific caching, batch, regional, and tool charges may affect the final cost.
Input · Standard
$0.10
Per 1M tokens
Cached input · Standard
Not available
No listed cached-input rate
Capabilities
Step 3.5 Flash Tools
Tools available when using Step 3.5 Flash through supported provider APIs.
Function calling
Supported
Structured outputs
Not supported
JSON mode
Not supported
Reasoning
Supported
Built-in web search
Not supported
Log probabilities
Not supported
Deterministic seed
Not supported
Parallel tool calls
Not supported
Prompt caching
Not supported
Strengths and limitations
Strengths
- Low input cost at $0.10 per million tokens suits high-volume workloads.
- 262K context supports large documents, repositories and extended conversations.
- Supports text & reasoning workloads in one model.
Limitations
- Real-world cost still depends on prompt length, response length and provider-specific billing rules.
- Large context capacity does not guarantee consistent retrieval across the entire prompt.
- Arena Elo and MMLU-Pro are directional; test accuracy, latency and reliability on your own workload before committing.
Arena Elo, MMLU-Pro and pricing figures are illustrative; validate current vendor terms before purchase.
Same provider