StepFun: Step 3.5 Flash (free)

Server-rendered model summary page for indexing/share previews. Use the interactive explorer for full filtering and comparison.

Match confidence: UnmatchedSource type: model_only

Context window

Arena overall rank

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Input price

$0.000 / 1M

Output price

$0.000 / 1M

Identifiers & provenance

Primary ID: stepfun/step-3.5-flash:free
OpenRouter ID: stepfun/step-3.5-flash:free
Canonical slug: stepfun/step-3.5-flash

Source semantics

Arena rank is a human-preference leaderboard signal, not a universal truth metric.
OpenRouter usage/popularity reflects adoption/traffic, not benchmark quality.
Pricing fields may differ by provider and can include extra modes beyond prompt/completion.

Read more on Methodology & data sources.

Description

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. It is a reasoning model that is incredibly speed efficient even at long contexts.

Raw fields snapshot

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