StepFun: Step 3.5 Flash
Analysis Summary
StepFun's paid Step 3.5 Flash shows a high agentic index alongside tool use and function calling support, paired with a 262K token context window. Its general intelligence score is modest, so it is better suited to structured, tool-driven tasks than open-ended complex reasoning.
The combination of agentic reliability and very low per-token pricing makes it a candidate for high-volume automation, workflow orchestration, and simple agent chains where cost efficiency matters more than top-tier reasoning depth.
It is a reasonable budget pick for agentic automation, though businesses needing deep analytical reasoning should pair it with a stronger model for complex decisions.
Assessed July 25, 2026
Editorial notes
Step 3.5 Flash from StepFun delivers a strong agentic score and very low pricing across a 262K context, though raw intelligence remains modest.
Rankings consider pricing, capabilities, benchmarks, and real-world applicability and are refreshed as new models launch. Feedback?
DFO Verdict
Step 3.5 Flash from StepFun delivers a strong agentic score and very low pricing across a 262K context, though raw intelligence remains modest.
How StepFun: Step 3.5 Flash compares
StepFun: Step 3.5 Flash ranks #112 of 395 AI models we track for overall intelligence, #52 of 302 for agentic tasks. Its 262K-token context window is larger than 79% of the models we list. At $0.10 per million input tokens it is cheaper than 68% of comparable models.
Dark bar = input Ā· light bar = output, scaled to the priciest peer.
1M tokens ā 8 full-length novels or ~2,500 pages of business documents in a single request.
Strongest on value. The pulled-in intelligence corner is the trade-off, and if the shape matters more than the price, this is your model.
Compare shapes side-by-side āPricing
| 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?
Pick the job that looks most like yours, then fine-tune with the sliders. Estimates update live.
A website chatbot handling around 100 customer conversations a day, a few short messages each.
Full calculator with 620 models ā 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.
