What is Step 3.5 Flash?

Step 3.5 Flash is an AI model by StepFun. Step 3.5 Flash is StepFun's most capable open-source foundation model.

How much does Step 3.5 Flash cost on Zeplik?

Input tokens cost 1.2 credits per million and output tokens 3.6 credits per million (1 credit = $0.10; the raw provider rates are $0.10 and $0.30 per million). New accounts start with free credits.

How long can a conversation with Step 3.5 Flash be?

Step 3.5 Flash has a 262K-token context window (262,144 tokens), which covers the conversation plus any documents you attach.

Does Step 3.5 Flash support images and tools?

Step 3.5 Flash is text-only and supports tool calling.

Step 3.5 Flash

Fast and lightTools

StepFun · Released January 2026

Step 3.5 Flash is StepFun's most capable open-source foundation model.

It belongs to StepFun's Step series, carried here in its Flash speed tiers.

Facts and pricing

Provider: StepFun
Context window: 262K tokens
Input price: 1.2 credits / 1M tokens ($0.10 raw)
Output price: 3.6 credits / 1M tokens ($0.30 raw)
Vision (image input): No
Tool calling: Yes
Extended reasoning: No

Credits are what Zeplik bills: 1 credit = $0.10, computed from the raw provider rate with a 1.20x margin. Raw prices shown per 1M tokens.

Try Step 3.5 Flash now

Or open Zeplik with Step 3.5 Flash already selected

What Step 3.5 Flash is best for

High-volume everyday tasks where speed and cost matter: summaries, drafts, quick questions
Long documents: the 262K-token window holds lengthy reports, contracts or papers whole
Tool use and agents: reliably calls functions, so it can search, run skills and drive workflows

Example prompts

Prompts that suit a fast and light model like Step 3.5 Flash:

Summarize this article in five bullet points
Rewrite this email to be shorter and friendlier
Give me ten name ideas for a hiking newsletter
Translate this paragraph to Spanish and keep the tone

StepFun family

Model	Context	Input cr/M	Output cr/M	Released
Step 5 Preview	1M	12.0	32.4	October 2026
Step 3.7 Flash	256K	2.4	13.8	May 2026
Step 3.5 Flash	262K	1.2	3.6	January 2026

Model comparisons

Frequently asked questions

What is Step 3.5 Flash?: Step 3.5 Flash is an AI model by StepFun. Step 3.5 Flash is StepFun's most capable open-source foundation model.
How much does Step 3.5 Flash cost on Zeplik?: Input tokens cost 1.2 credits per million and output tokens 3.6 credits per million (1 credit = $0.10; the raw provider rates are $0.10 and $0.30 per million). New accounts start with free credits.
How long can a conversation with Step 3.5 Flash be?: Step 3.5 Flash has a 262K-token context window (262,144 tokens), which covers the conversation plus any documents you attach.
Does Step 3.5 Flash support images and tools?: Step 3.5 Flash is text-only and supports tool calling.

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