Step 3.5 Flash
StepFun Step 3.5 Flash — pricing, 262k context window, API cost calculator and alternatives.
By StepFun
Specs
- Provider
- StepFun
- Slug
- stepfun/step-3-5-flash
- Capabilities
- tools, json_mode
Pricing freshness
- Tier
- standard
- Currency
- USD
- As of
- 2026-05-08 17:08 UTC
Pricing history
Tracking Step 3.5 Flash pricing since 2026-05-08. We'll plot the chart here once it changes.
Quickstart — call Step 3.5 Flash from your app
curl https://openrouter.ai/api/v1/chat/completions \
-H "Content-Type: application/json" \
-H "Authorization: Bearer $OPENROUTER_API_KEY" \
-d '{
"model": "stepfun/step-3-5-flash",
"messages": [{"role": "user", "content": "Hello!"}]
}'Official docs: https://openrouter.ai/docs
# pip install openai
from openai import OpenAI
client = OpenAI(
base_url="https://openrouter.ai/api/v1",
api_key=os.environ["OPENROUTER_API_KEY"],
)
resp = client.chat.completions.create(
model="stepfun/step-3-5-flash",
messages=[{"role": "user", "content": "Hello!"}],
)
print(resp.choices[0].message.content)Official docs: https://openrouter.ai/docs
// npm install openai
import OpenAI from "openai";
const client = new OpenAI({
baseURL: "https://openrouter.ai/api/v1",
apiKey: process.env.OPENROUTER_API_KEY,
});
const resp = await client.chat.completions.create({
model: "stepfun/step-3-5-flash",
messages: [{ role: "user", content: "Hello!" }],
});
console.log(resp.choices[0].message.content);Official docs: https://openrouter.ai/docs
Related models
Similar capabilities, context window, and price tier — drawn from across the catalog so you can compare alternatives in one click.
Frequently asked questions
What is Step 3.5 Flash?
Step 3.5 Flash is a large language model API from StepFun with a 262k-token context window. It costs $0.1 per 1M input tokens and $0.3 per 1M output tokens.
How much does Step 3.5 Flash cost?
Step 3.5 Flash is priced at $0.1 per 1M input tokens and $0.3 per 1M output tokens via the StepFun API. A 50/50 input/output workload of 1M total tokens costs about $0.2.
What is the context window of Step 3.5 Flash?
Step 3.5 Flash supports up to 262k tokens of context per request — roughly 524 pages of English text or 32768 lines of code at a typical density.
Does Step 3.5 Flash support vision, tool use, or JSON mode?
Step 3.5 Flash supports tool/function calling and structured JSON mode. It does not support image input (vision).
Who makes Step 3.5 Flash?
Step 3.5 Flash is built and operated by StepFun. Pricing, context window, and capabilities on this page are refreshed nightly from StepFun's public catalog.
Can I self-host Step 3.5 Flash?
Step 3.5 Flash is API-only — its weights are not publicly distributed by StepFun, so it cannot be self-hosted today.