Step 3.7 Flash

stepfun/step-3.7-flash

A chat model with a 256K-token context window, at $0.21 per million input tokens and $1.2075 per million output tokens.

Details

Maker: stepfun
Kind: Chat
Context window: 256,000 tokens
Max output: 256,000 tokens
Input: $0.21 per million tokens
Cached input: $0.042 per million tokens, 80% off
Cache write: Same as input
Output: $1.2075 per million tokens
Capabilities: Reasoning, tool use, vision
Takes: Text, image
Returns: Text
Zero data retention: Not on every provider
No training on requests: Not on every provider
Released: 2026-05-28

Description

StepFun’s flagship multimodal reasoning model. Powered by a 198B-parameter / 11B-activation sparse MoE architecture, with native support for image and video understanding.

Call it

curl

curl https://phantom.codes/v1/chat/completions \
  -H "Authorization: Bearer $PHANTOM_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "stepfun/step-3.7-flash",
    "messages": [
      {"role": "user", "content": "Hello"}
    ]
  }'

Set PHANTOM_KEY to your key. Any OpenAI client works with the base URL https://phantom.codes/v1.

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