# Grok 4 Fast

id: ent_grok-4-fast  
kind: product  
timeline: /timelines/grok-4-fast.md  
page: /record/grok-4-fast  
same_as: https://asof.is/record/grok-4-fast (how to cite the id: /identifiers.md)  

cost-efficient reasoning model by xAI, 2M context

## Fact pages

One page per fact: the current value with its sources, then every dated value and what replaced what. Fetch any of them as markdown.

- [Grok 4 Fast release date](/record/grok-4-fast/model_release.md)
- [Grok 4 Fast retirement](/record/grok-4-fast/retired.md)
- [Grok 4 Fast context window](/record/grok-4-fast/context_window.md)

## Current state

What the record asserts: claims that held, valid by their sources or primary-sourced at confidence 0.7 or more. Unverified, disputed, retracted and review-marked claims are listed below, labelled, not here.

- [Grok 4 Fast](/record/grok-4-fast.md) | context_window | 2M token | valid 2025-09-19 to present | conf 0.95 | valid | [clm_B23CF82119F1](/claim/clm_B23CF82119F1.md)
  sources: https://x.ai/news/grok-4-fast

## All claims

One claim per line, newest first. Superseded claims stay visible.

- [Grok 4 Fast](/record/grok-4-fast.md) | retired | grok-4-fast-reasoning | valid 2026-05-15 to present | conf 0.95 | valid | [clm_88F24D97EEE0](/claim/clm_88F24D97EEE0.md)
  sources: https://docs.x.ai/developers/migration/may-15-retirement
- [Grok 4 Fast](/record/grok-4-fast.md) | context_window | 2M token | valid 2025-09-19 to present | conf 0.95 | valid | [clm_B23CF82119F1](/claim/clm_B23CF82119F1.md)
  sources: https://x.ai/news/grok-4-fast

## Posts and Hugging Face repos (1)

Dated items from the entity's own feeds, and the days its Hugging Face repositories were created, newest first.

- [Grok 4 Fast](/record/grok-4-fast.md) | model_release | Grok 4 Fast | valid 2025-09-19 to present | conf 0.95 | valid | [clm_DFB0958C2D0F](/claim/clm_DFB0958C2D0F.md)
  sources: https://x.ai/news/grok-4-fast

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AsOf is a temporal fact ledger: a structured, dated, sourced record of what is true and what changed, built for AI retrieval.