Grok 4.1 Fast API

x-ai/grok-4-1-fast-reasoning
Grok 4.
Context
2M tokens
Input
$1.625 / 1M tokens
Output
$3.25 / 1M tokens
Released
Nov 20, 2025

How to use Grok 4.1 Fast API

Install any OpenAI-compatible SDK, point it at api.aimlapi.com/v1, and set the model to x-ai/grok-4-1-fast-reasoning.
import requests

r = requests.post(
    "https://api.aimlapi.com/v1/chat/completions",
    headers={"Authorization": "Bearer " + AIMLAPI_KEY},
    json={
      "model": "x-ai/grok-4-1-fast-reasoning",
      "messages": [
        {
          "role": "user",
          "content": "Hello!"
        }
      ]
    },
)
print(r.json())
const r = await fetch("https://api.aimlapi.com/v1/chat/completions", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.AIMLAPI_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "model": "x-ai/grok-4-1-fast-reasoning",
    "messages": [
      {
        "role": "user",
        "content": "Hello!"
      }
    ]
  }),
});
console.log(await r.json());
curl -X POST https://api.aimlapi.com/v1/chat/completions \
  -H "Authorization: Bearer $AIMLAPI_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"x-ai/grok-4-1-fast-reasoning","messages":[{"role":"user","content":"Hello!"}]}'

OpenAI-compatible — swap the base URL and it works with your existing SDK.

Grok 4.1 Fast API Pricing

TypePrice
Input
$1.625 / 1M tokens
Output
$3.25 / 1M tokens
Cached input
$0.26 / 1M tokens

Grok 4.1 Fast Benchmarks

BenchmarkScoreWhat it measuresSourceRetrieved
Intelligence
20.4
Composite score across standardised reasoning, knowledge and problem-solving evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026
Math
89.3
Composite score across standardised mathematics evaluations, measured independently by Artificial AnalysisSourceSeptember 12, 2026

Grok 4.1 Fast vs other models

ModelInputOutputContextBest for
Grok 4.1 Fast
This page
$1.625 / 1M tokens
$3.25 / 1M tokens
2M tokens
Coding + agents
$6.5 / 1M tokens
$39 / 1M tokens
1M tokens
Reasoning + agents
$2.6 / 1M tokens
$13 / 1M tokens
1M tokens
Balanced coding + agents
$3.9 / 1M tokens
$19.5 / 1M tokens
1M tokens
Long-context, multimodal & agentic workflows
$0.65 / 1M tokens
$3.9 / 1M tokens
1M tokens
Reasoning + agents

Frequently asked questions

Grok 4.1 Fast has a 2,000,000 tokens context window and can return up to 1,999,000 tokens.

Grok 4.1 Fast takes image, text as input and returns text.

Use x-ai/grok-4-1-fast-reasoning as the model id. Requests go to https://api.aimlapi.com/v1/chat/completions.

Grok 4.1 Fast is priced at input $1.625 / 1M tokens, output $3.25 / 1M tokens, cached input $0.26 / 1M tokens.

Yes, Grok 4.1 Fast can stream responses as they are generated.

Yes, Grok 4.1 Fast accepts image input alongside text.

Grok 4.1 Fast was built by xAI .

It is designed for agentic tool calling with advanced reasoning, and supports multimodal image and text input.

Start building with Grok 4.1 Fast

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