Azure AI Foundry
grok-4-fast-reasoning model retirement
Stopped workingSubscribe to Azure AI FoundryShare
On May 1, 2026, Azure AI Foundry retired model grok-4-fast-reasoning. Calls targeting model grok-4-fast-reasoning fail since that date.
What to use instead of grok-4-fast-reasoning
Migrate to grok-4-1-fast-reasoning, which stops working on May 19, 2027. No permanent replacement is named yet.
In Azure AI Foundry's words
Model: grok-4-fast-reasoning; Version: 1; Lifecycle: Retired; Retirement date: 2026-05-01; Replacement: grok-4-1-fast-reasoning
Facts
- API
- Azure AI Foundry
*.services.ai.azure.com - Model
grok-4-fast-reasoning- Released
- December 18, 2025 (models.dev)
- Kind
- Model retirement
- Takes effect
- May 1, 2026
- Calls after that day
- Fail
- Source
- Deprecations page
- Last updated
- Verified
- , against Azure AI Foundry's own pages
Questions
When does grok-4-fast-reasoning shut down?
Calls to the model grok-4-fast-reasoning on Azure AI Foundry stopped working on May 1, 2026.
What happens to calls after May 1, 2026?
They have failed since May 1, 2026.
When was grok-4-fast-reasoning released?
grok-4-fast-reasoning was released on December 18, 2025, according to models.dev.
How do I find the calls this hits in my code?
Okapi reads your repository, finds the calls this change hits and opens a pull request with the fix. It never commits to your branches: every change comes as a pull request you review.
grok-4-fast-reasoning on other APIs 1
-
xAI
grok-4-fast-reasoningModel retirement Redirected
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You fixed this one by hand.
Okapi opens the pull request with the fix before the next breaking change reaches your code.