step-3.5-flash

completions

byopenrouter

step-3.5-flash

completions

Published by: stepfunProvider:

openrouter

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.

Released

Feb 2, 2026

Knowledge

Aug 6, 2025

License

Apache-2.0

Context

256K

Input

$0.1 / 1M tokens

Output

$0.3 / 1M tokens

Cached

$0.02 / 1M tokens

Capabilities: tools, reasoning

Accepts: text

Returns: text

Released Feb 2, 2026Knowledge Cutoff: Aug 6, 2025License: Apache-2.0

Context: 256K Input: $0.1 / 1M tokensOutput: $0.3 / 1M tokensCached: $0.02 / 1M tokensCapabilities: tools, reasoningAccepts: textReturns: text

Access step-3.5-flash through LangDB AI Gateway

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Benchmark Results for step-3.5-flash

Category Performance Scores:

Science: Score 71.46 (Top 36% - Rank #126)
Writing: Score 55.03 (Top 43% - Rank #150)
Academia: Score 60.45 (Top 19% - Rank #67)
Marketing: Score 53.62 (Top 41% - Rank #143)
Programming: Score 31.60 (Top 26% - Rank #91)

Overall Performance: 54.433393939393945 average score across all categories

Detailed Benchmark Scores:

Benchmark	Score	Percentile	Domain
HLE	19.10	Top 18%	General Knowledge
GPQA	83.10	Top 18%	STEM (Physics, Chemistry, Biology)
SciCode	40.40	Top 21%	Scientific
AA Coding Index	31.60	Top 26%	Programming
AAII	37.80	Top 19%	General

GPQA Score: 83.10 - Graduate-level reasoning benchmark

Model Comparison:

Provider: openrouter

Model Type: completions

Context Size: 256000 tokens

Comparing against 348 models in the database

Category Scores

Benchmark Tests

View Other Benchmarks

HLE

19.1

General Knowledge

GPQA

83.1

STEM (Physics, Chemistry, Biology)

SciCode

40.4

Scientific

AA Coding Index

31.6

Programming

AAII

37.8

General

Metric	HLE	GPQA	SciCode	AA Coding Index	AAII
Score	19.1	83.1	40.4	31.6	37.8

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Code Examples

Integration samples and API usage

Code Samples for step-3.5-flash

Python SDK Example:

from openai import OpenAI

client = OpenAI(
    base_url="https://api.us-east-1.langdb.ai/projects/<your_project_id>",
    api_key="<your_api_key>"
)

response = client.chat.completions.create(
    model="step-3.5-flash",
    messages=[
        {"role": "user", "content": "Hello, how are you?"}
    ]
)

print(response.choices[0].message.content)

TypeScript SDK Example:

import OpenAI from 'openai';

const client = new OpenAI({
    baseURL: "https://api.us-east-1.langdb.ai/projects/<your_project_id>",
    apiKey: "<your_api_key>"
});

const response = await client.chat.completions.create({
    model: "step-3.5-flash",
    messages: [
        { role: "user", content: "Hello, how are you?" }
    ]
});

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

cURL Example:

curl -X POST "https://api.us-east-1.langdb.ai/projects/<your_project_id>/v1/chat/completions" \
  -H "Authorization: Bearer <your_api_key>" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "step-3.5-flash",
    "messages": [
        {"role": "user", "content": "Hello, how are you?"}
    ]
  }'

Model: step-3.5-flash

Provider: openrouter

API Endpoint: $https://api.us-east-1.langdb.ai

Create API Key

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step-3.5-flash by openrouter - AI Model Details, Pricing, and Performance Metrics

step-3.5-flash

step-3.5-flash

Access step-3.5-flash through LangDB AI Gateway

Category Scores

Benchmark Tests

Compare with Similar Models

Code Examples

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