Grok 4.1 Fast (Reasoning)
Redirected. Grok 4.1 Fast (Reasoning) is active on 3 platforms, with no shutdown date announced. xAI names Grok 4.3 as the replacement.
- Next shutdown
- None setNo date on 3 platforms
- Arena Text
- 1,430#57 of 128 · Arena
- Arena WebDev
- 1,242#63 of 69 · Arena
- Context window
- 2Mtokens
- Released
- Nov 19, 2025xAI
Dates on every platform
| Platform | Model ID and status | Deprecated | Shuts down | Replacement |
|---|---|---|---|---|
| Azure AI FoundryMicrosoft: Model retirement schedule - Microsoft Foundry (opens in a new tab) · checked Oct 14, 2026 | grok-4-1-fast-reasoning:1Active | – | None set | – |
| Google Vertex AIGoogle Cloud: Gemini Enterprise Agent Platform release notes (opens in a new tab) · checked Oct 14, 2026 | grok-4.1-fast-reasoningShut down · also xai/grok-4.1-fast-reasoning | Shut down | – | |
| xAI APIxAI: Grok Model Retirement on May 15, 2026 (opens in a new tab) · checked Oct 14, 2026 | grok-4-1-fast-reasoningShut down | – | Shut down | Grok 4.3 |
Since the retirement, requests to grok-4-1-fast-reasoning are served by grok-4.3 with low reasoning effort and billed at grok-4.3 rates.
Since May 15, 2026, requests to grok-4-1-fast-reasoning on xAI API are answered by Grok 4.3, with no error. Behavior and price follow the newer model.
What breaks when you move off Grok 4.1 Fast (Reasoning)
- Pricing
- Defaults
- Parameters
Intelligence
| Benchmark | Publisher | Score | Rank | Published |
|---|---|---|---|---|
| Arena Text | Arena | 1,430 ± 2 | #57 of 128 | Oct 8, 2026 |
| Arena WebDev | Arena | 1,242 ± 6 | #63 of 69 | Oct 8, 2026 |
Arena (arena.ai), https://arena.ai/leaderboard
Change history
ShutdownGrok 4.1 Fast models shut down on Agent PlatformGoogle Vertex AI
Google stopped serving grok-4.1-fast-reasoning and grok-4.1-fast-non-reasoning through Model as a Service on Gemini Enterprise Agent Platform.
- Platform
- Google Vertex AI
- Announced
Source: Google Cloud, Gemini Enterprise Agent Platform release notes (opens in a new tab); Google Cloud, Grok 4.1 Fast (opens in a new tab)
RedirectSix Grok models retired on the xAI API and redirected to Grok 4.3xAI API3 breaks
xAI retired grok-4-1-fast-reasoning, grok-4-1-fast-non-reasoning, grok-4-fast-reasoning, grok-4-fast-non-reasoning, grok-4-0709 and grok-3. The slugs still resolve: requests are served by grok-4.3 instead of returning an error.
- Platform
- xAI API
- Models
- Grok 4.1 Fast (Reasoning), Grok 4.1 Fast (Non-Reasoning), Grok 4 Fast (Reasoning), Grok 4 Fast (Non-Reasoning), Grok 4, Grok 3
- Replacement
- Grok 4.3
- PricingRequests to the retired slugs are billed at grok-4.3 rates, not the rates of the original model.
- DefaultsReasoning slugs are served with low reasoning effort and non-reasoning slugs with none; set medium or high explicitly for deeper reasoning.
- Parametersgrok-4.20 and newer models silently ignore logprobs and top_logprobs.
Source: xAI, Grok Model Retirement on May 15, 2026 (opens in a new tab); xAI, Models (opens in a new tab)