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StepFun: Step 5 Preview

step-5-preview

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Step 5 Preview costs $1.30 per million input tokens and $3.51 per million output tokens, supports 1.05M context, and is available through the OpenAI-compatible API.

Step 5 Preview is StepFun's 600B sparse MoE frontier model for production-scale agents, activating 27B parameters per token. It is built for software engineering, long-horizon tool use, research, professional knowledge work, and finance, with native text, image, and video understanding and a 1M-token context window.

Modalities

Text + Image + Video → Text

Input / output price

$1.30 / $3.51 per 1M

Context

1.05M · max output 66K

Capabilities

ReasoningVisionTool callingLong context

Pricing

Billed per token actually used and deducted from your credits.

ItemUSD per 1M tokens
Input$1.30
Output$3.51
Cached input$0.065

Calculator

Drag the sliders to estimate what this model will cost.

Per request
$0.00671
Per day
$3.35
Per month (30 days)
$100.62

Step 5 Preview: input $1.3/M · output $3.51/M · cached input $0.065/M

Request with these settings
curl https://api.geniusrelaygpt.com/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "step-5-preview", "max_tokens": 800,
       "messages": [{"role": "user", "content": "…"}]}'

Code samples

OpenAI-compatible. Set the base URL to https://api.geniusrelaygpt.com/v1 and the model to step-5-preview.

curl https://api.geniusrelaygpt.com/v1/chat/completions \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "step-5-preview",
    "stream": true,
    "messages": [{"role": "user", "content": "Hello"}]
  }'

Use it in a client: Cursor · Cline · SillyTavern · Codex

Parameters

Common OpenAI parameters can be passed as-is.

temperaturetop_pmax_tokensstreamstoppresence_penaltyfrequency_penaltyseed

FAQ

How is Step 5 Preview billed?
Input is $1.30 and output is $3.51 per million tokens; cached input is $0.065. The charge for every request is listed in Usage Logs in the console.
How long is the context window?
1.05M tokens. In a long conversation every turn is billed for the full input, so keep the history under control.
Does it support streaming?
Yes. Add "stream": true to the request to receive server-sent events in the OpenAI format.
Step 5 Preview API pricing · GeniusRelay