What is the context window of X-Ai/Grok-4-Fast-Non-Reasoning, and how long can its output be?

The context window is 2M tokens (2,000,000), and the maximum output is also 2M tokens (2,000,000).

Can X-Ai/Grok-4-Fast-Non-Reasoning read images, audio, video or PDFs?

Yes, it can read text, image, audio and video. PDFs are not listed as a supported input.

Does X-Ai/Grok-4-Fast-Non-Reasoning support tool calling?

Yes, tool calling (function calling) is supported.

Does X-Ai/Grok-4-Fast-Non-Reasoning have a reasoning or thinking mode?

No, a reasoning mode is not supported.

Where does X-Ai/Grok-4-Fast-Non-Reasoning rank on Arena?

Rank 135 on Arena Text (Arena's own rank) with a score of 1418.

What are the closest alternatives to X-Ai/Grok-4-Fast-Non-Reasoning?

Closest alternatives, matched on model kind and release date (no comparable price), are ERNIE 5.0 by Baidu, Composer 1 by Cursor and Composer 1.5 by Cursor.

What is the best open-weight alternative to X-Ai/Grok-4-Fast-Non-Reasoning?

X-Ai/Grok-4-Fast-Non-Reasoning is closed. The highest-ranked open-weight model on Arena Text is Kimi K3 at rank 19.

What is the difference between X-Ai/Grok-4-Fast-Non-Reasoning and X-Ai/Grok-4-Fast-Reasoning?

The listed specs show no difference: both have a context of 2M tokens (2,000,000) and both were released on December 18, 2025.

Is X-Ai/Grok-4-Fast-Non-Reasoning open source or open weights?

No, X-Ai/Grok-4-Fast-Non-Reasoning is closed.

Who made X-Ai/Grok-4-Fast-Non-Reasoning and when was it released?

X-Ai/Grok-4-Fast-Non-Reasoning was made by xAI and released on December 18, 2025.

X-Ai/Grok-4-Fast-Non-Reasoning

xAI

X-Ai/Grok-4-Fast-Non-Reasoning

Developer	xAI
Release date	December 18, 2025
Family	Grok
Generation	Grok 4
Level
Context window	2M tokens
Max output	2M tokens
Input	Text, image, audio, video
Output	Text
Weights	Closed
Website	x.ai
Links	Model card Docs

Part of a series on

xAI

Context: 2Mtokens
Released: 10mo ago

Fast Grok model for responsive chat, reasoning, and tool-assisted work

How it compares

Level

LightweightThe lab's smallest, cheapest and lowest-latency hosted line, built for high volume and simple tasks.

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Additional source evidence

Source model: xai/grok-4-fast-non-reasoning
Source family: grok
Last updated: 2025-12-18
Model context: 2M
Model output limit: 2M
Open weights: No
File attachments: Yes
Reasoning: No
Tool calling: Yes
Temperature control: Yes

Complete source record (JSON)

{
  "id": "xai/grok-4-fast-non-reasoning",
  "name": "X-Ai/Grok-4-Fast-Non-Reasoning",
  "description": "Fast Grok model for responsive chat, reasoning, and tool-assisted work",
  "family": "grok",
  "last_updated": "2025-12-18",
  "attachment": true,
  "reasoning": false,
  "tool_call": true,
  "temperature": true,
  "modalities": {
    "input": [
      "text",
      "image",
      "audio",
      "video"
    ],
    "output": [
      "text"
    ]
  },
  "limit": {
    "context": 2000000,
    "output": 2000000
  },
  "release_date": "2025-12-18",
  "open_weights": false
}