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Deprecations / Migrate

Migrate off Grok 4 Fast (Reasoning)

Retired

Grok 4 Fast (Reasoning) has been retired and shut down on 15 May 2026. xAI's official replacement is Grok 4.3. The cheapest comparable model we track is Grok Build 0.1 (xAI) at $1.25 per 1M tokens blended.

Last verified: 13 Aug 2026 · sourced from official provider documentation

StatusRetiredxAI
Shut down15 May 2026plan ahead
Official replacementGrok 4.3$1.56 /M blendedCheapest alternativeGrok Build 0.1$1.25 /M blended
What changes

Grok 4 Fast (Reasoning) → Grok 4.3

SpecGrok 4 Fast (Reasoning)Grok 4.3
StatusRetiredGA
Blended price /1M—$1.56
Input / output /1M—$1.25 / $2.50
Context window—1M
Max output——
Modalitytext-in, image-in, text-outtext-in, image-in, text-out
Knowledge cutoff——

API string was grok-4-fast-reasoning → switch to grok-4.3. See Grok 4.3's full spec sheet →

Cheapest alternatives

Budget-friendly replacements for Grok 4 Fast (Reasoning)

Generally-available models that match Grok 4 Fast (Reasoning)'s capabilities, ranked by blended price. Every number is computed from official catalog prices.

ModelBlended /1MInput / outputContext
Grok Build 0.1
xAI
$1.25$1 / $2256K
Grok 4.20 (0309) Reasoning
xAI
$1.56$1.25 / $2.501M
Grok 4.20 (0309) Non-Reasoning
xAI
$1.56$1.25 / $2.501M
FAQ

Migrating off Grok 4 Fast (Reasoning)

What replaces Grok 4 Fast (Reasoning)?

xAI's recommended migration for Grok 4 Fast (Reasoning) is Grok 4.3. The cheapest comparable model in our catalog is Grok Build 0.1 (xAI) at $1.25/1M blended.

Is Grok 4 Fast (Reasoning) still available?

No — Grok 4 Fast (Reasoning) has been retired (shut down 15 May 2026) and is no longer available via xAI's API.

What is the cheapest alternative to Grok 4 Fast (Reasoning)?

Grok Build 0.1 (xAI) is the cheapest generally-available alternative we track that matches Grok 4 Fast (Reasoning)'s capabilities, at $1 per 1M input and $2 per 1M output tokens ($1.25/1M blended).

Browse the full deprecation watch → or see Grok 4 Fast (Reasoning)'s full spec sheet →