MODELS / STEPFUN

Step 5 Preview

Step 5 Preview is StepFun’s flagship AI model for agentic coding, professional knowledge work, and financial analysis. Built on a sparse Mixture-of-Experts architecture with 600B total parameters and 27B active per token, it combines a 1M-token context window with vision input.…

TEXTIMPLICIT-CACHINGVISION
1M
CONTEXT WINDOW
-
MAX OUTPUT TOKENS
$1
INPUT PRICE / 1M TOKENS
$2.70
OUTPUT PRICE / 1M TOKENS
QUICKSTART

Call it in one request.

OpenAI-compatible: change the base URL, and the setup is complete.

curl https://enterprise.blackbox.ai/v1/chat/completions \
  -H "Authorization: Bearer $BLACKBOX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "blackboxai/stepfun/step-5-preview",
    "messages": [{ "role": "user", "content": "Hello!" }],
    "stream": true
  }'
SPECIFICATIONS

The full spec sheet.

Context, pricing, modalities, routing, and deployment: everything Step 5 Preview supports, in one table.

MODEL ID
blackboxai/stepfun/step-5-preview
DEVELOPED BY
Stepfun
MODEL TYPE
Text
RELEASED
Sep 20, 2026
CONTEXT WINDOW
1M
MAX OUTPUT TOKENS
-
INPUT MODALITIES
text, image
OUTPUT MODALITIES
text
INPUT PRICE
$1 / 1M tokens
OUTPUT PRICE
$2.70 / 1M tokens
CACHE READ
$0.05 / 1M tokens
REASONING
Not supported
DATA RETENTION
Standard retention
DEDICATED DEPLOYMENT
Not available (closed-weight model)
SUPPORTED PARAMETERS
max_tokenstemperaturestop