opendunes

Step 3.5 Flash

by StepfunReleased 29 January 2026

Step 3.5 Flash reads and writes text, thinks before it answers, and keeps about 260 pages in mind at once while staying fast on long inputs. StepFun calls it its most capable open model, released under the Apache 2.0 licence so you can download it and run it yourself, and it supports connected tools for agent work.

TakesText
GivesText
Open in chatCreate API keyCompare

What it costs

You pay for what each request uses. No subscription, no minimum.

≈ 0,083 DA per message3 000 DA buys about 36 000 messages

One message, the ordinary use

1 000 tokens sent× 33,28 DA per 1M0,033 DA
500 tokens back× 99,85 DA per 1M0,050 DA
Total≈ 0,083 DA

Every rate

Meter↑ you send↓ comes back
Text tokens33,28 DA99,85 DA

per 1M tokens

Answer a quick question≈ 0,030 DA
Reply to a customer email≈ 0,060 DA
Write a one-page draft≈ 0,10 DA
Translate a full page of text≈ 0,10 DA
Summarise a 10-page report≈ 0,29 DA
When you pay
After the answer, from your balance. Nothing is held.
Why it varies
A longer question or a longer answer costs more.
After each one
The exact charge shows on the request.
DepositDeposits from 50 DA, with Edahabia or CIB.

Where your request runs

One company runs this model. OpenDunes sends every request to it. DA per 1M tokens: ↑ what you send · ↓ what comes back.

SiliconFlowUnited States…
↑ Sent, per 1M
33,28 DA
↓ Back, per 1M
99,85 DA
Latency
…
Throughput
…
Provider↑ Sent↓ BackLatencyThroughputUptime
SiliconFlowUnited States33,28 DA99,85 DA………

You pay the price of the provider that served your request. Prices read 15:18 · speed over the last 30 minutes · uptime over 3 days.

See it in action

Real requests, real replies. Try any of them yourself — one click, pre-filled.

Writing
You send

Two lines to welcome a shop in Oran.

It replied

Welcome to our new shop in Oran — fresh bread every morning, and coffee the way the city likes it. Come in, the first cup is on us.

Try in Chat Lab

Try your own request — same model, pre-selected.

Open Chat Lab

Call it in code

Swap the base URL and the key. Your OpenAI code runs unchanged.

POST /v1/chat/completions
Base URL
https://opendunes.com/v1
Model ID
stepfun/step-3.5-flash
import os
from openai import OpenAI

client = OpenAI(
    base_url="https://opendunes.com/v1",
    api_key=os.environ["OPENDUNES_API_KEY"],
)

resp = client.chat.completions.create(
    model="stepfun/step-3.5-flash",
    messages=[{"role": "user", "content": "Two lines to welcome a shop in Oran."}],
)

print(resp.choices[0].message.content)
pip install openaiFull reference for this route
Sign in to run it

Runs this request once on your balance.

Parameters you can send

Standard OpenAI fields, grouped by what they control. Anything not listed is accepted and ignored.

Shaping the reply

How long, how varied, where to stop.

max_tokenstemperaturetop_ptop_kfrequency_penalty

Reasoning

Let it think before answering — and see the thinking.

reasoninginclude_reasoning

Tools

Let the model call your functions.

toolstool_choice

Questions about Step 3.5 Flash

  • How much does Step 3.5 Flash cost in dinars?

    About 0,083 DA per message. ↑ 33,28 DA · ↓ 99,85 DA per 1M tokens.

  • Is Step 3.5 Flash free? Can I try it?

    No. You pay per use from your balance, with no subscription. Try it in Chat at the same price.

  • What is Step 3.5 Flash best for?

    Step 3.5 Flash reads and writes text, thinks before it answers, and keeps about 260 pages in mind at once while staying fast on long inputs. StepFun calls it its most capable open model, released under the Apache 2.0 licence so you can download it and run it yourself, and it supports connected tools for agent work.

  • How do I pay for Step 3.5 Flash without an international card?

    Deposit dinars with your Edahabia or CIB card. Every model, Step 3.5 Flash included, is paid from that balance. No foreign card, no conversion.

  • Does Step 3.5 Flash work in Arabic, French or Darja?

    Stepfun names no languages for Step 3.5 Flash. Arabic, French and Darja: not stated.

  • Can it read PDFs, images or a whole book?

    It reads text. Up to 262K tokens in one request, about 260 pages. It writes up to 49 000 words at once.

  • Is Step 3.5 Flash open source?

    Yes, its weights are public. Open weights on Hugging Face

  • Who makes Step 3.5 Flash, and when was it released?

    Stepfun. Released 29 January 2026.

Other Stepfun models, priced in dinars

See all Stepfun models
Step 5 PreviewStepfun · Oct 8, 2026

Step 5 Preview reads text, pictures and video and writes text, keeping about 1,000 pages in mind at once. StepFun calls it its flagship for long tasks: it does well at building software and at expert office work, finance above all, across big codebases and document sets, where it uses tools and refines its result step by step.

Thinks firstUses your tools1 000 pages at once
≈0,78 DAper message
View model
Step 3.7 FlashStepfun · May 28, 2026

Step 3.7 Flash reads text, pictures and video and writes text, keeping about 260 pages in mind at once. You pick a high, medium or low thinking level to trade speed and cost against depth. StepFun designs it for coding, long jobs that use connected tools, filling in the exact tables you specify, and long-document work.

Thinks firstUses your tools260 pages at once
≈0,26 DAper message
View model