StepFun
StepFun: Step 5 Preview
stepfun/step-5-preview
Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters). It performs strongly in software engineering and professional knowledge work, with particular strength in finance. It is designed for extended tasks that span large codebases and documents, using tools and refining results over multiple steps.
Input
$1
/ 1M tokens
Output
$2.7
/ 1M tokens
Context window
1.05M
tokens
Limits
Context
1,048,576
tokens
Max output
64,000
6.1% of the context window
Parameters
604,339,504,832
Model facts
Author
StepFun
Tokenizer
Other
Modality
Text + Image + Video -> Text
License
Other
Created
Oct 8, 2026
Hugging Face
stepfun-ai/Step-5-Preview
Reasoning
RequiredDefault MediumHighMediumLow
Publication status
Hugging Face: verifiedLicense: publishedParameter count: published
Modalities
Input · TextInput · ImageInput · VideoOutput · Text
Generation controls
Frequency penaltyInclude reasoningLogit biasLogprobsMax tokensMin pPresence penaltyReasoningReasoning effortRepetition penaltyResponse formatSeedStopStructured outputsTemperatureTool choiceToolsTop kTop logprobsTop p
Capability scores
43.7
Intelligence index
Better than 90% of models compared