Models/xAI/Grok 4.5

xAI: Grok 4.5

Textgrok-4.5

xAI's Grok 4.5: a frontier model for coding, agentic tasks and reasoning.

API docs

Playgroundgrok-4.5

Temperature

Top-p

Max tokens

Reasoning

Seed

Frequency penalty

Presence penalty

Web search

Throughput138 tok/s

24hnow

Latency0.89 s

24hnow

Specifications

Authorxai

ModalityText

Context256K tokens

Input$1.70/M tokens$2.00/M tokens

Output$5.10/M tokens$6.00/M tokens

Savings−15%

Capabilitiesreasoning, tool calling, image input

Quick start

from openai import OpenAI

client = OpenAI(
    base_url="https://api.altrouter.ai/v1",
    api_key="ar-...",
)

resp = client.chat.completions.create(
    model="grok-4.5",
    messages=[{"role": "user", "content": "Hello!"}],
)
print(resp.choices[0].message.content)

Same OpenAI-compatible endpoint — just swap base_url and key.

API

OpenAI-compatible chat completions endpoint, with SSE streaming.

POST/v1/chat/completions

Body parameters

modelstringrequired"grok-4.5"

The model id.

messagesarrayrequired

The conversation: [{ role, content }].

streambooleandefault false

Stream the response over SSE.

temperaturenumber0–2default 1

Sampling randomness: lower is more deterministic, higher more creative.

top_pnumber0–1default 1

Nucleus sampling — the probability mass to sample from.

max_tokensnumber1–32000

Maximum tokens to generate.

reasoning_effortenumlow · medium · highdefault medium

Thinking budget for reasoning models.

seednumber0–2147483647

Seed for reproducibility.

frequency_penaltynumber-2–2

Penalizes tokens by their existing frequency.

presence_penaltynumber-2–2

Penalizes tokens that have already appeared.

web_searchbooleandefault false

Server-side web search — answers with live data.

Structured fields (tools, response_format, stop and more) are in the full parameter reference.

Response

idstring

Completion id.

choicesarray

Completions. Each: index, message { role, content, reasoning_content, tool_calls }, finish_reason.

usageobject

Tokens: prompt_tokens, completion_tokens, total_tokens.

Example

cURLPythonJSON

curl https://api.altrouter.ai/v1/chat/completions \
  -H "Authorization: Bearer ar-..." \
  -H "Content-Type: application/json" \
  -d '{
  "model": "grok-4.5",
  "messages": [
    {
      "role": "user",
      "content": "Hello!"
    }
  ],
  "reasoning_effort": "medium"
}'

Errors

400Invalid request.

401Missing or invalid API key.

402Insufficient credits, or the key’s spending cap is exhausted.

404Model not found.

429Rate limit exceeded.