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AI model reference · 2026

Step 5 Preview

StepFunModel details, evidence, and API facts

Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters).

Text generation
Image input
Reasoning
Provider endpoint accepts tool parameters
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Context window
1,000,000 tokens
Maximum output
64,000 tokens
Base provider API input
$1.00 / 1M tokens
Base provider API rate
Published evidence
0 benchmarks, 1 Arena result

Overview

About Step 5 Preview

A concise catalog overview. Technical limits and published evaluation evidence are listed separately below.

Step 5 Preview is StepFun's flagship model for agentic work, built on a sparse Mixture-of-Experts architecture (27B active / 600B total parameters).

text
multimodal
reasoning

Published evaluations

Benchmark results

Only results mapped to this exact model and backed by a named source appear here. Different evaluation protocols are not treated as interchangeable.

No reviewed benchmark result is available for this exact model yet. We leave this section empty instead of assigning a nearby model’s score.

Human preference

Arena results

Arena scores come from blind human preference votes. They are reported separately from task benchmarks and are not used as substitutes for missing benchmark results.

Arena results for Step 5 Preview
CategoryScoreRankVotesStatus
Arena TextBlind human preference score for text responses.1,454±11#742,701Published

Technical reference

Specifications and API facts

Technical limits and reference provider prices come from the current catalog unless a reviewed external source is listed. Missing values stay marked as unavailable.

Model
Provider
StepFun
Release date
Not available in reviewed sources
Catalog added
Oct 8, 2026
Context window
1,000,000 tokens
Maximum output
64,000 tokens
Knowledge cutoff
Not available in reviewed sources
License
Not available in reviewed sources
Capabilities and API
Input types
Text, Image, Video
Output types
Text
Reasoning
Supported
Provider endpoint tool parameters
Accepts tool parameters
Base provider API input
$1.00 / 1M tokens
Base provider cached input
$0.05 / 1M tokens
Base provider API output
$2.70 / 1M tokens

These are reference provider API rates, not Writingmate checkout charges. Access in Writingmate follows the allowances of your Writingmate plan.

Provenance

Sources and update status

Source links are attached to the facts and evaluations they support. Catalog-only values are not presented as independently verified claims.

Evidence last updated Oct 5, 2026.

Catalog record updated Oct 8, 2026.

Catalog-added dates describe when a model entered the catalog, not necessarily its public release date.

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