StepFun Step 3.5 Flash

Step 3.5 Flash by StepFun excels in the Coding category, where it ranks #117 with a composite score of 67/100. 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.... It is particularly strong in areas highlighted by its top benchmark performance and adoption metrics, making it suitable for both individual developers and enterprise teams looking for a reliable coding solution.

Step 3.5 Flash is priced at $0.10 per million input tokens and $0.30 per million output tokens (USD). Contact the provider for volume discounts and enterprise pricing. Pricing is competitive within the coding category and reflects the model's quality-to-cost ratio.

In the Coding category, Step 3.5 Flash holds rank #117 out of 340 models tracked. Its quality rank is #117 and adoption rank is #117. You can use our comparison tool at /compare to see detailed side-by-side metrics with specific alternatives. Key differentiators include its composite scoring across benchmarks, community sentiment, and real-world adoption rates.

Step 3.5 Flash has been evaluated across 6 different signals. Its strongest areas include Capabilities (67/100), Benchmarks (66/100), Pricing (100/100). These scores are derived from industry-standard benchmarks, community ratings, and real-world performance metrics. The composite score of 67/100 reflects a weighted combination of all tracked signals.

Step 3.5 Flash is a paid model, though some providers may offer trial credits or limited free tiers for evaluation. Check StepFun's website for current free tier availability and promotional offers.

Step 3.5 Flash supports a 262K token context window (262,144 tokens total). That translates to roughly 196,608 words in a single prompt. This is large enough to process entire codebases, research papers, or long conversation histories in one shot.

Step 3.5 Flash can generate up to 66K output tokens (65,536 tokens) per response. That is roughly 49,152 words. This is enough for generating complete code files, detailed reports, or long-form content in a single response.

Step 3.5 Flash supports function/tool calling, structured JSON output, extended reasoning/chain-of-thought, streaming responses. Function calling lets you integrate it with external APIs and tools programmatically. These capabilities determine which workflows and integrations the model can handle natively.

Yes, Step 3.5 Flash is an open-source model. You can download the weights, run it locally, fine-tune it for your use case, or deploy it on your own infrastructure. Many cloud providers also offer hosted versions if you prefer not to manage the infrastructure yourself. Self-hosting gives you full control over data privacy and eliminates per-token API costs.

Step 3.5 Flash was developed by StepFun. It was released on January 29, 2026. You can access it through StepFun's API or download the model weights directly. Check our provider page for all models from StepFun and how they compare against each other.

Pick Step 3.5 Flash when you need a solid balance of cost and capability for everyday development tasks, content generation, and standard API integrations. If your task is straightforward text completion or classification, a cheaper model might give you 90% of the quality at a fraction of the price. Run a quick benchmark on your actual use case before committing.

You can access Step 3.5 Flash through StepFun's API using standard HTTP requests or their official SDK. Most providers support OpenAI-compatible endpoints, so switching between models often requires changing just the model name in your API call. Streaming is supported for real-time token-by-token output. For production use, implement proper error handling, rate limiting, and cost monitoring.