AI Rate Card

Step3 · aihubmix

Step3 is a multimodal reasoning model released by StepFun. It uses a Mixture‑of‑Experts (MoE) architecture with 321 billion total parameters and 38 billion activation parameters. The model follows an end‑to‑end design that reduces decoding cost while delivering top‑tier performance on vision‑language reasoning tasks. Thanks to the combined use of Multi‑Head Factorized Attention (MFA) and Attention‑FFN Decoupling (AFD), Step3 remains highly efficient on both flagship and low‑end accelerators. During pre‑training, it processed over 20 trillion text tokens and 4 trillion image‑text mixed tokens, covering more than ten languages. On benchmarks for mathematics, code, and multimodal tasks, Step3 consistently outperforms other open‑source models.

Base modelAll models on this baseAll models of the providerto the provider

All StepFun models at every provider

Input, $/1M $1.10

Output, $/1M $2.75

Context —

Accepts —

Last checked 04.11.2026 12:00:14 UTC

Source provider's page

Price alerts

Sign in to follow the price

API

OpenAI-compatible API: the official OpenAI SDKs work with this base URL. Replace YOUR_API_KEY with your key from the provider.

API base URL
https://aihubmix.com/api/v1
Endpoint
https://aihubmix.com/api/v1/chat/completions
Model id
stepfun-ai/step3
curl
curl https://aihubmix.com/api/v1/chat/completions \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model": "stepfun-ai/step3", "messages": [{"role": "user", "content": "Hello!"}], "max_tokens": 256}'
Python
import requests

r = requests.post(
    "https://aihubmix.com/api/v1/chat/completions",
    headers={"Authorization": "Bearer YOUR_API_KEY"},
    json={
      "model": "stepfun-ai/step3",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ],
      "max_tokens": 256
    },
)
print(r.json())
JavaScript
const r = await fetch("https://aihubmix.com/api/v1/chat/completions", {
  method: "POST",
  headers: {Authorization: "Bearer YOUR_API_KEY", "Content-Type": "application/json"},
  body: JSON.stringify({
    "model": "stepfun-ai/step3",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ],
    "max_tokens": 256
  }),
});
console.log(await r.json());
Request (JSON)
{
  "model": "stepfun-ai/step3",
  "messages": [
    {
      "role": "user",
      "content": "Hello!"
    }
  ],
  "max_tokens": 256
}
Response (JSON)
{
  "id": "chatcmpl-...",
  "object": "chat.completion",
  "model": "stepfun-ai/step3",
  "choices": [
    {
      "index": 0,
      "message": {
        "role": "assistant",
        "content": "Hi! How can I help?"
      },
      "finish_reason": "stop"
    }
  ],
  "usage": {
    "prompt_tokens": 9,
    "completion_tokens": 12,
    "total_tokens": 21
  }
}

The address is taken from the provider's model list; check it against the provider's documentation.

Provider's API documentation

Source: AI Rate Card, https://airatecard.com/en/c/offer%3Aaihubmix%7Cstepfun-ai/step3, prices checked 2026-11-04; seller's page: https://aihubmix.com

Technical details

ID: offer:aihubmix|stepfun-ai/step3