StepFun: Step 3.5 Flash
Analysis Summary
StepFun's Step 3.5 Flash is a compact general-purpose model focused on affordable production use. It offers a 262K context window, tool use, and function calling, providing the basic infrastructure for retrieval, workflow automation, structured generation, and lightweight agent tasks. Its text-only modality keeps the deployment profile straightforward.
For an agency, the model is best suited to high-volume SEO briefs, metadata generation, classification, content transformations, and routine support flows where predictable cost matters more than difficult reasoning. The available intelligence measure places it below the level required for complex research, nuanced strategy, or autonomous coding. It should therefore be used behind clear prompts, validation rules, and escalation paths.
Low input and output pricing support bulk workloads, while the large context window helps with lengthy source material. Adopt it as a volume model for structured tasks, not as the primary choice for high-stakes client analysis.
Assessed August 9, 2026
Editorial notes
Step 3.5 Flash combines a 262K context window with tool use, function calling, and low token pricing, making it suited to structured automation and high-volume content workflows, though reasoning depth is limited.
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DFO Verdict
Step 3.5 Flash combines a 262K context window with tool use, function calling, and low token pricing, making it suited to structured automation and high-volume content workflows, though reasoning depth is limited.
How StepFun: Step 3.5 Flash compares
StepFun: Step 3.5 Flash ranks #144 of 428 AI models we track for overall intelligence. Its 262K-token context window is larger than 72% of the models we list. At $0.10 per million input tokens it is cheaper than 69% of comparable models.
Dark bar = input · light bar = output, scaled to the priciest peer.
1M tokens ≈ 8 full-length novels or ~2,500 pages of business documents in a single request.
Strongest on value. The pulled-in technical corner is the trade-off, and if the shape matters more than the price, this is your model.
Compare shapes side-by-side →Pricing
| Token Type | Cost per 1M tokens | Cost per 1K tokens |
|---|---|---|
| Input | $0.10 | $0.000100 |
| Output | $0.30 | $0.000300 |
What would StepFun: Step 3.5 Flash cost your business?
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A website chatbot handling around 100 customer conversations a day, a few short messages each.
Full calculator with 717 models → Price Calculator
These numbers get smaller with the right architecture.
We route routine calls to cheap models and save StepFun: Step 3.5 Flash for the hard ones. Most clients cut their estimate by 60-80%.
Talk to our teamAbout StepFun: Step 3.5 Flash
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..
Frequently asked questions about StepFun: Step 3.5 Flash
How much does StepFun: Step 3.5 Flash cost?
StepFun: Step 3.5 Flash costs $0.10 per million input tokens and $0.30 per million output tokens.
What is the context window of StepFun: Step 3.5 Flash?
StepFun: Step 3.5 Flash has a context window of 262,144 tokens (262K).
What can StepFun: Step 3.5 Flash do?
StepFun: Step 3.5 Flash supports tool use and function calling.
Who created StepFun: Step 3.5 Flash?
StepFun: Step 3.5 Flash is developed by StepFun and was released on January 29, 2026.