X Ai model

Grok 4.1 Fast Reasoning API

This id is x-ai/grok-4.1-fast-reasoning. Its input price is $0.2 per 1M tokens. If you need a published context window, walk away from this id.

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X AiPlatform curatedCatalog
ThinkingFunction CallingVision
Input price$0.2 / 1M tokens
Output price$0.5 / 1M tokens
Context length2M tokens
Max output8.2k tokens

What is Grok 4.1 Fast Reasoning API in NextModel?

This id is x-ai/grok-4.1-fast-reasoning. Its input price is $0.2 per 1M tokens. If you need a published context window, walk away from this id.

grok-4-1-fast-reasoning via NextModel: 2M-token context; $0.2 / 1M tokens in / $0.5 / 1M tokens out per 1M tokens. Capabilities: streaming.

Best use cases

  • Call this id if your workload fits the catalog use case quality, streaming is useful, and an unpublished context window is acceptable.
  • You need the listed capabilities on this catalog entry.
  • The listed price fits the workload better than the siblings in the same family.

When not to use

  • Do not call this id if you require a published context window.
  • Do not call it if you need first-party CacheSafety data, because first-party CacheSafety is unpublished for this model.
  • A required number is unpublished in the catalog snapshot.

OpenAI-compatible code example

request.sh
curl https://api.nextmodel.app/v1/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $NEXTMODEL_API_KEY" \
  -d '{"model":"x-ai/grok-4.1-fast-reasoning","messages":[{"role":"user","content":"Reply with OK."}]}'

Switching models only changes the model field.

Try it in the playground

Similar alternatives

X AiCatalog

grok-4-1-fast-non-reasoning

grok-4-1-fast-non-reasoning via NextModel: 2M-token context; $0.2 / 1M tokens in / $0.5 / 1M tokens out per 1M tokens. Capabilities: streaming.

$0.2 / 1M tokensInput$0.5 / 1M tokensOutput2MContext
Best forGeneral chat via X Ai, API workloads
Streaming
Platform curatedCurated and maintained in the NextModel catalog
View details
X AiCatalog

grok-4-20-non-reasoning

grok-4-20-non-reasoning via NextModel: 256k-token context; $1.25 / 1M tokens in / $2.50 / 1M tokens out per 1M tokens. Capabilities: streaming.

$1.25 / 1M tokensInput$2.50 / 1M tokensOutput256kContext
Best forGeneral chat via X Ai, API workloads
Streaming
Platform curatedCurated and maintained in the NextModel catalog
View details
X AiCatalog

grok-4-20-reasoning

grok-4-20-reasoning via NextModel: 256k-token context; $1.25 / 1M tokens in / $2.50 / 1M tokens out per 1M tokens. Capabilities: streaming.

$1.25 / 1M tokensInput$2.50 / 1M tokensOutput256kContext
Best forGeneral chat via X Ai, API workloads
Streaming
Platform curatedCurated and maintained in the NextModel catalog
View details

Compare grok-4-1-fast-reasoning

grok-4-1-fast-reasoning vs grok-4-1-fast-non-reasoninggrok-4-1-fast-reasoning vs grok-4-20-non-reasoninggrok-4-1-fast-reasoning vs grok-4-20-reasoninggrok-4-1-fast-reasoning vs Kimi K3 GLBgrok-4-1-fast-reasoning vs GPT-5 Codex

Reading

Articles that explain grok-4-1-fast-reasoning

FAQ

grok-4-1-fast-reasoning API questions

What model id do I send for Grok 4.1 Fast Reasoning?

Send x-ai/grok-4.1-fast-reasoning to https://api.nextmodel.app/v1 with your OpenAI SDK. If that id is missing from /v1/models, the page is stale.

What does the catalog list for price and context?

Grok 4.1 Fast Reasoning is listed at $0.2 / 1M tokens input and $0.5 / 1M tokens output. Context window: not published in catalog.

What should I treat as unverified?

Do not call this id if you require a published context window. Do not call it if you need first-party CacheSafety data, because first-party CacheSafety is unpublished for this model.

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