Step 3.5 Flash

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....

by StepFun

Overview

Quick stats across all benchmark runs.

Score

29%

3 benchmarks

Avg Latency

23.3s

21 requests

Pricing

$0.10 in / $0.30 out

per 1M tokens

Context

262K

tokens

Alternatives

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No alternatives found

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Benchmark Performance

How this model performs across different benchmarks

Benchmark	Score	Rank
Explain Like I'm 5	56%	23 / 47
Categorization Bench	45%	30 / 54
Money Boy Cultural Literacy Test	29%	87 / 107

Price vs Performance

Compare cost efficiency across all models

Current model (baseline)

Other models (relative score)

Y-axis shows score difference from shared benchmarks. X-axis uses log scale.

Score Over Time

Performance trends across all benchmark runs

Benchmark Activity

Number of benchmark runs over time

Quickstart

View on OpenRouter

Get started with this model using OpenRouter

import { OpenRouter } from "@openrouter/sdk";

const openrouter = new OpenRouter({
  apiKey: "<OPENROUTER_API_KEY>"
});

const completion = await openrouter.chat.completions.create({
  model: "stepfun/step-3.5-flash",
  messages: [
    {
      role: "user",
      content: "Hello!"
    }
  ]
});

console.log(completion.choices[0].message.content);

Get your API key at openrouter.ai/keys

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