step-3.7-flash

step-3.7-flash is a efficient-tier language model from StepFun. step-3.7-flash is a proprietary model available exclusively through StepFun's API. The Step 3 family is StepFun's model series for this capability tier.

step-3.7-flash is priced at $0.2/1M input tokens and $1.15/1M output tokens. Output tokens are 5.7× more expensive than input tokens — this ratio reflects the sequential nature of autoregressive generation, which requires a separate forward pass per output token versus parallel processing of all input tokens simultaneously. At a typical usage pattern of 1,000 input tokens and 500 output tokens per call, step-3.7-flash costs approximately $0.78 per 1,000 API calls. StepFun does not publish a prompt caching rate for this model, so repeated long contexts are billed at the standard $0.2/1M input rate.

Its 256K-token context window is in the top tier for production models, enabling full-document analysis, long multi-turn conversations, and large codebase understanding without chunking. Median latency (P50 time-to-first-token) is approximately 300ms — suitable for interactive applications where sub-second response is acceptable. Throughput is approximately 200 tokens/second — fast enough to stream responses at reading speed with headroom for concurrent requests. Maximum output length is 8K tokens — adequate for most generation tasks including essays, code functions, and detailed responses.

step-3.7-flash is best suited to cost, speed, chat. Supported capabilities include function calling / tool use for agentic workflows, streaming token output for real-time UIs. Function calling support makes it suitable for building AI agents, structured data extraction pipelines, and any workflow requiring the model to invoke external APIs or return typed JSON. When evaluating this model for a specific workload, the most important factors are: context window (does your input fit?), output price (how long are your generations?), and latency (is this interactive or batch?). The pricing table above shows how step-3.7-flash compares to similar models across these dimensions.

step-3.7-flash sits in the efficient tier — optimized for speed and cost while maintaining solid quality, ideal for high-volume or latency-sensitive workloads. Unlike open-weights alternatives, step-3.7-flash is only available via StepFun's API — there is no self-hosted option, which simplifies deployment but creates vendor dependency. When comparing step-3.7-flash to alternatives, use the similar models section on this page to find models at comparable price points with different capability tradeoffs. The intelligence score (74/100) reflects aggregate benchmark performance — a useful proxy for general capability, though real-world performance varies significantly by task type. Always test with your specific prompts and use case before committing to a model for production.