Step 5 Preview · Office #43,180

What it is

Calls itself “MoE”.

• Calls itself: MoE

“Step 5 Preview is StepFun's open-weight MoE for coding, financial research and long-running agents.”

Where it puts itself

Claims “new flagship model”.

• Superlative claim: new flagship model

“Today, we're introducing Step 5 Preview, our new flagship model for agentic work.”

Who it sells to

Sells to developers. Made for agents.

• Sells to: developers
• Made for: agents

“Step 5 Preview is available today through our products and API.”

“Step 5 Preview is StepFun's open-weight MoE for coding, financial research and long-running agents.”

How it runs

A API. Hosted in the cloud. Offers an API. Open source. AI is the core of the product.

• Kind: api
• Runs where: cloud / hosted
• API: yes
• Open source: yes
• AI role: core to the product

“Step 5 Preview is available today through our products and API.”

“The model will be released with open weights on October 15.”

What it works with

Names Claude Opus 5, GPT-6 Astra and 5 more on its pages.

• Names: Claude Opus 5 · GPT-6 Astra · SGLang · +4

“Claude Opus 5 (Max)”

“GPT-6 Astra (Max)”

What it offers as proof

Live, no waitlist. Claims “600B total parameters”. Instant signup. Publishes docs.

• Number claimed: 600B total parameters
• Instant signup: yes

“Try Step 5 Preview”

“Step 5 Preview has 600B total parameters, with 27B active per token, and supports a 1M-token context window and vision input.”