stepfun

StepFun: Step 3.5 Flash

StepFun: Step 3.5 Flash is designed for handling text inputs with a substantial context length of 262,144 tokens and supports tools and reasoning, making it suitable for complex tasks that require extensive data processing. The model does not support structured output, which means its outputs will be in plain text. This model might be a good choice for those who need to work with large volumes of text and value the ability to use external tools and engage in advanced reasoning processes. With a blended benchmark score of 42.4 across one independent benchmark, it performs well but is not at the top tier. Given its pricing at $0.1 per million input tokens and $0.3 per million output tokens, it offers a balanced cost for users who require robust text processing capabilities.

Quality Score
94/100
price + capability + benchmarks
Input Price
$0.10
per 1M tokens
Output Price
$0.30
per 1M tokens
Context Window
262,144
tokens

Benchmark results

Independent, published benchmarks. Blended score 42.4 across 1 benchmark, last refreshed 2026-07-23. How scoring works →

BenchmarkMeasuresScore
AI Index broad capability composite 42.9
Model ID
stepfun/step-3.5-flash
Vendor
stepfun
Released
January 2026
Tokenizer
Other
Input Modalities
text
Output Modalities
text
Max Output
65,536 tokens
Tool Calling
✓ supported
Structured Output
not supported
Reasoning Mode
✓ supported
Vision
text only
Audio
no
Moderated
no

What it costs in practice

Computed from the current $0.10/M input and $0.30/M output rates. Run your own numbers →

JobTokensCost
Summarize a 50-page report 30k in / 1.5k out under $0.01
Classify 1,000 customer emails 500k in / 50k out $0.07
A month of a busy support chatbot 5M in / 2M out $1.10

Similar models

Quick answers

How much does StepFun: Step 3.5 Flash cost?
$0.10 per million input tokens and $0.30 per million output tokens.
What is StepFun: Step 3.5 Flash's context window?
262,144 tokens, roughly 393 pages of text in a single request.
Does StepFun: Step 3.5 Flash support tool calling?
It supports tool calling, a reasoning mode.
Can StepFun: Step 3.5 Flash process images?
No, it is text-only on the input side.