stepfun

StepFun: Step 3.5 Flash (free)

by stepfun

OpenRouter
Tools Reasoning Long Context

About

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.

Specifications

Context Length 256K
Max Output Tokens 256K
Modality text->text
Input text
Output text
Supported Parameters frequency_penalty, include_reasoning, max_tokens, reasoning, stop, temperature, tools, top_p
Content Moderation No

Error Rate

Based on feedback reported by Free LLM Router users. Error rate reflects the percentage of requests that encountered issues such as rate limiting, unavailability, or errors. Learn more.

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Model 1h 6h 24h 7d 30d
StepFun: Step 3.5 Flash (free) - - - - 85.7%

Availability

Available 41 of 41 tracked days. Daily snapshots show whether this model was accessible as a free model on OpenRouter.

FebMar
ModelDays181920212223242526272812345678910111213141516171819
StepFun: Step 3.5 Flash (free)30

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Frequently Asked Questions

Is StepFun: Step 3.5 Flash (free) free to use?

Yes, StepFun: Step 3.5 Flash (free) is completely free to use through OpenRouter. You can access it via the Free LLM Router API at no cost.

What is the context window for StepFun: Step 3.5 Flash (free)?

StepFun: Step 3.5 Flash (free) supports a context window of 256K tokens (256,000 tokens).

What is the maximum output length for StepFun: Step 3.5 Flash (free)?

StepFun: Step 3.5 Flash (free) can generate up to 256K tokens (256,000 tokens) per response.

Does StepFun: Step 3.5 Flash (free) support function calling (tools)?

Yes, StepFun: Step 3.5 Flash (free) supports function calling / tool use, enabling it to interact with external APIs and services.

Does StepFun: Step 3.5 Flash (free) support reasoning?

Yes, StepFun: Step 3.5 Flash (free) supports reasoning capabilities, allowing it to show its step-by-step thought process.