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Grok 4.1 Fast (Reasoning)

Retired

Retired from xAI API on 2026-05-15 12:00 PM PT; redirects to grok-4.3 with 'low' reasoning effort, slug still resolves. Specs/pricing no longer on docs; left null. (Was ~$0.20/$0.50 per M per third-party trackers before retirement; not officially current.)

Grok 4.1 Fast (Reasoning) by xAI is tracked live in our LLM catalog. It has been retired (shut down 15 May 2026); the recommended migration is Grok 4.3.

Last verified: 26 Sep 2026 · sourced from official provider documentation

Retired on 15 May 2026

Lifecycle warning

This model has been retired. Recommended migration: Grok 4.3.

Read the Grok 4.1 Fast (Reasoning) migration guide → replacement & cheapest alternatives

Provider
xAI
Status
Retired
Input price
—
Output price
—
Cached input
—
Blended price
—
Context window
—
Max output
—
Modality
text-in, image-in, text-out
Open weights
No — API only
Knowledge cutoff
—
Released
—
API string
grok-4-1-fast-reasoning

Source: xAI official documentation ↗

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FAQ

Grok 4.1 Fast (Reasoning) — questions & answers

Is Grok 4.1 Fast (Reasoning) still available?

Grok 4.1 Fast (Reasoning) has been retired and is no longer available. Its scheduled shutdown date is 15 May 2026. The recommended migration is Grok 4.3.

Does Grok 4.1 Fast (Reasoning) support image or vision input?

Yes — Grok 4.1 Fast (Reasoning) accepts image input. Listed modalities: text-in, image-in, text-out.

Can I self-host Grok 4.1 Fast (Reasoning)?

No — Grok 4.1 Fast (Reasoning) is proprietary. Its weights are not publicly released, so it is available only through xAI's API (or hosted partners), not for self-hosting.

What is the API model string for Grok 4.1 Fast (Reasoning)?

The API model identifier for Grok 4.1 Fast (Reasoning) is "grok-4-1-fast-reasoning" when calling xAI's API.