# Grok 4.1 Fast

> Grok 4.1 Fast is a proprietary language model from xAI, released on 19 Nov 2025. It accepts text and images and generates text, with a 2M-token context window and up to 30K output tokens per response.

Source page: https://www.aimodel.directory/models/grok-4-1-fast
Last verified: 4 Oct 2026

## Specifications

- **Developer:** xAI
- **Release date:** 19 Nov 2025 (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Status:** Generally available (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Weights:** Proprietary (API only) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Context window:** 2M (2,000,000 tokens) (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Max output:** 30K tokens (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Input:** Text and images (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Output:** Text (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Reasoning mode:** No (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Tool calling:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)
- **Structured output:** Yes (source: models.dev, https://github.com/sst/models.dev/blob/dev/providers/ofox/models/x-ai/grok-4.1-fast.toml)

## API pricing (USD per 1M tokens)

| Provider | Input | Output | Cached input | Context |
|---|---|---|---|---|

## FAQ

### What is the context window of Grok 4.1 Fast?

Grok 4.1 Fast has a context window of 2,000,000 tokens (2M) and can generate up to 30,000 tokens in a single response, according to models.dev.

### Is Grok 4.1 Fast open source?

No. Grok 4.1 Fast is a proprietary model; xAI has not released its weights.

### When was Grok 4.1 Fast released?

xAI released Grok 4.1 Fast on 19 Nov 2025, according to models.dev.

---
Data licensed CC BY 4.0. Cite as: AI Model Directory, "Grok 4.1 Fast", https://www.aimodel.directory/models/grok-4-1-fast