Grok 4.1 Fast

Grok 4.1 Fast is a reasoning model by xAI with vision, function calling, web search, prompt caching, structured output — designed for complex, multi-step problem solving where accuracy matters more than speed. It supports a 2M token context window with up to 2M tokens of output. Priced at $1.25 per million input tokens and $2.5 per million output tokens. Access Grok 4.1 Fast through Inworld Router with OpenAI SDK compatibility, built-in failover, and intelligent routing across providers.

→Function Calling Web Search Reasoning Prompt Caching Response Schema Vision reasoning Capability

Step 1 — Create Router

cURL

curl --location 'https://api.inworld.ai/router/v1/routers' \
--header 'Authorization: Basic <your-api-key>' \
--header 'Content-Type: application/json' \
--data '{
  "name": "compare-frontier-models",
  "defaultRoute": {
      "route_id": "default",
      "variants": [\
        {\
          "variant": {\
              "variant_id": "xai/grok-4-1-fast-a",\
              "model_id": "xai/grok-4-1-fast"\
          },\
          "weight": 33\
        },\
        {\
          "variant": {\
              "variant_id": "xai/grok-3-mini-fast-b",\
              "model_id": "xai/grok-3-mini-fast"\
          },\
          "weight": 33\
        },\
        {\
          "variant": {\
              "variant_id": "xai/grok-3-mini-fast-beta-c",\
              "model_id": "xai/grok-3-mini-fast-beta"\
          },\
          "weight": 34\
        }\
      ]
  }
}'

Python

import requests

response = requests.post(
    "https://api.inworld.ai/router/v1/routers",
    headers={
        "Authorization": "Basic <your-api-key>",
        "Content-Type": "application/json",
    },
    json={
        "name": "compare-frontier-models",
        "defaultRoute": {
            "route_id": "default",
            "variants": [\
                {\
                    "variant": {\
                        "variant_id": "xai/grok-4-1-fast-a",\
                        "model_id": "xai/grok-4-1-fast"\
                    },\
                    "weight": 33\
                },\
                {\
                    "variant": {\
                        "variant_id": "xai/grok-3-mini-fast-b",\
                        "model_id": "xai/grok-3-mini-fast"\
                    },\
                    "weight": 33\
                },\
                {\
                    "variant": {\
                        "variant_id": "xai/grok-3-mini-fast-beta-c",\
                        "model_id": "xai/grok-3-mini-fast-beta"\
                    },\
                    "weight": 34\
                }\
            ]
        }
    },
)
print(response.json())

JavaScript

const response = await fetch(
"https://api.inworld.ai/router/v1/routers",
{
    method: "POST",
    headers: {
      Authorization: "Basic <your-api-key>",
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      name: "compare-frontier-models",
      defaultRoute: {
        route_id: "default",
        variants: [\
          {\
            variant: {\
              variant_id: "xai/grok-4-1-fast-a",\
              model_id: "xai/grok-4-1-fast",\
            },\
            weight: 33,\
          },\
          {\
            variant: {\
              variant_id: "xai/grok-3-mini-fast-b",\
              model_id: "xai/grok-3-mini-fast",\
            },\
            weight: 33,\
          },\
          {\
            variant: {\
              variant_id: "xai/grok-3-mini-fast-beta-c",\
              model_id: "xai/grok-3-mini-fast-beta",\
            },\
            weight: 34,\
          },\
        ],
      },
    }),
}
);
const data = await response.json();
console.log(data);

Step 2 — Chat Completion

cURL

curl --location 'https://api.inworld.ai/v1/chat/completions' \
--header 'Authorization: Basic <your-api-key>' \
--header 'Content-Type: application/json' \
--data '{
  "model": "inworld/compare-frontier-models",
  "messages": [{"role": "user", "content": "Hello!"}]
}'

Python

from openai import OpenAI

client = OpenAI(
    api_key="<your-api-key>",
    base_url="https://api.inworld.ai/v1",
)

response = client.chat.completions.create(
    model="inworld/compare-frontier-models",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(response.choices[0].message.content)

JavaScript

import OpenAI from "openai";

const client = new OpenAI({
    apiKey: "<your-api-key>",
    baseURL: "https://api.inworld.ai/v1",
});

const response = await client.chat.completions.create({
    model: "inworld/compare-frontier-models",
    messages: [{ role: "user", content: "Hello!" }],
});
console.log(response.choices[0].message.content);

Grok 4.1 Fast pricing and providers

Access Grok 4.1 Fast through xAI via Inworld Router or Realtime API. By using the AI provider(s) below you acknowledge you reviewed and agree to their terms listed in the Legal section under the AI provider's name.

Other xAI models available through Inworld

Compare Grok 4.1 Fast with other xAI models available through Inworld Router or Realtime API.

Start building with Grok 4.1 Fast

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