grok-4-fast-reasoning — Retired — shutdown 2026-05-01 or May 15, 2026 — sources disagree
For grok-4-fast-reasoning, provider is Microsoft Azure / Foundry; lifecycle status is Retired; shutdown / retirement date is disputed: 2026-05-01 per learn.microsoft.com, May 15, 2026 per docs.x.ai; recommended replacement is disputed: grok-4-1-fast-reasoning per learn.microsoft.com, grok-4.3 with low reasoning effort per docs.x.ai; platform / deployment scope is Azure / Microsoft Foundry, recorded from its source on 2026-08-28; source re-checked 2026-10-13.
- Provider
- Microsoft Azure / Foundry our reading
- xAI per docs.x.ai
- Model ID / API name
- grok-4-fast-reasoning verified
- Human-readable model name
- grok-4-fast-reasoning verified
- Lifecycle status
- Retired verified
- Shutdown / retirement date
- 2026-05-01 sources disagree
- Recommended replacement
- grok-4-1-fast-reasoning sources disagree
- Platform / deployment scope
- Azure / Microsoft Foundry our reading
- xAI API per docs.x.ai
Values marked our reading are our classification of what the source says — the source does not print them in those words. The quote below is the evidence for each one; judge it yourself.
What the source says
| grok-4-fast-reasoning | 1 | Retired | 2026-05-01 | grok-4-1-fast-reasoning |
— learn.microsoft.com, retrieved 2026-08-28
Where each value comes from
The value above is stated away from the sentence quoted with the answer, so the passage that states it is shown here too.
Shutdown / retirement date
| Model | Version | Lifecycle | Retirement date | Replacement | | --- | --- | --- | --- | --- | | grok-3 | 1 | Retired | 2026-05-01 | grok-4 | | grok-3-mini | 1 | Retired | 2026-05-01 | grok-4-1-fast-reasoning | | grok-4 | 1 | GA | — | — | | grok-4-1-fast-non-reasoning | 1 | GA | — | — | | grok-4-1-fast-reasoning | 1 | GA | — | — | | grok-4-20-non-reasoning | 1 | Preview | 2027-04-06 | — | | grok-4-20-reasoning | 1 | Preview | 2027-04-06 | — | | grok-4-fast-non-reasoning | 1 | Retired | 2026-05-01 | grok-4-1-fast-non-reasoning | | grok-4-fast-reasoning | 1 | Retired | 2026-05-01 | grok-4-1-fast-reasoning |
— all from learn.microsoft.com, retrieved 2026-08-28
Sources disagree
More than one authority states this, and they do not state the same thing. Both are reproduced with the source each came from — deciding between them is yours, not ours.
Shutdown / retirement date
learn.microsoft.com says shutdown / retirement date is 2026-05-01, as of 2026-08-28.
| grok-4-fast-reasoning | 1 | Retired | 2026-05-01 | grok-4-1-fast-reasoning |
https://learn.microsoft.com/en-us/azure/foundry/openai/concepts/model-retirement-schedule
docs.x.ai says shutdown / retirement date is May 15, 2026, as of 2026-09-09.
As we continue advancing Grok, we are retiring several earlier models to focus fully on our newest generation. Effective May 15, 2026 at 12:00 PM PT, the following models will be retired from the xAI API: grok-4-1-fast-reasoning grok-4-1-fast-non-reasoning grok-4-fast-reasoning grok-4-fast-non-reasoning grok-4-0709 grok-code-fast-1 grok-3 grok-imagine-image-pro
https://docs.x.ai/developers/migration/may-15-retirement
Recommended replacement
learn.microsoft.com says recommended replacement is grok-4-1-fast-reasoning, as of 2026-08-28.
| grok-4-fast-reasoning | 1 | Retired | 2026-05-01 | grok-4-1-fast-reasoning |
https://learn.microsoft.com/en-us/azure/foundry/openai/concepts/model-retirement-schedule
docs.x.ai says recommended replacement is grok-4.3 with low reasoning effort, as of 2026-09-09.
As we continue advancing Grok, we are retiring several earlier models to focus fully on our newest generation. Effective May 15, 2026 at 12:00 PM PT, the following models will be retired from the xAI API: grok-4-1-fast-reasoning grok-4-1-fast-non-reasoning grok-4-fast-reasoning grok-4-fast-non-reasoning grok-4-0709 grok-code-fast-1 grok-3 grok-imagine-image-pro
Where the other sources' values come from
These values were taken from a passage elsewhere on the other source's page, not from the row quoted with it above.
Recommended replacement
grok-4-fast-reasoning | grok-4.3 with low reasoning effort |
— docs.x.ai, retrieved 2026-09-09
Sources
- learn.microsoft.comhttps://learn.microsoft.com/en-us/azure/foundry/openai/concepts/model-retirement-schedule
- docs.x.aihttps://docs.x.ai/developers/migration/may-15-retirement