Grok 4 Fast Reasoning
Grok 4 Fast Reasoning is a legacy integration reference; evaluate Grok 4.7 before starting new work.
- Family
- Grok 4
- Released
- 2025-09-01
- Context
- 2M
- Architecture
- Decoder Only
- Specialization
- general
- Openness
- Proprietary
- License
- ProprietaryRestricted
- Weights
- Not released
- Code
- Unknown
- Training
- Pretrained
No tracked provider pricing is available yet.
This model is deprecated. xAI recommends switching to Grok 4.7.
About
Grok 4 Fast Reasoning is a September 2025 xAI model retiring on 2026-05-15; use Grok 4.3 for current API work.
Providers
No active provider routes are tracked for this model.
Deprecated provider routes(2)
| Provider | Status | Catalog ID |
|---|---|---|
| Microsoft Foundry | DeprecatedRetired May 1, 2026 | — |
| xAI Console | DeprecatedRetired May 15, 2026 | grok-4-fast-reasoning |
Available via routers & gateways(6)
LiteLLM
GatewayOpen-source Python SDK and proxy server that unifies 100+ LLM APIs behind a single OpenAI-compatible interface, with load balancing, cost tracking, and configurable failover.
OpenRouter
HybridUnified hybrid gateway to 500+ models from 80+ providers via a single OpenAI-compatible API, with an optional Auto Router that selects a model per prompt from market spend data.
Portkey
GatewayProduction AI gateway routing to 1,600+ LLMs with failover, load balancing, caching, and guardrails; MIT-licensed open-source core is self-hostable. Now part of Palo Alto Networks as Prisma AIRS AI Gateway.
Azure AI Foundry Model Router
RouterMicrosoft Azure AI Foundry's native model router that uses a trained ML model to route each prompt in real time to the optimal Azure-hosted model, with Balanced/Cost/Quality mode selection and automatic failover.
Helicone
GatewayObservability-first AI gateway with routing, caching, rate limiting, and request tracing; Apache-2.0 open-source platform with a managed hosted tier for logging and analytics.
Kong AI Gateway
GatewayMulti-LLM AI gateway built on Kong Gateway 3.x, adding semantic routing, load balancing, guardrails, and MCP traffic analytics as plugins over Kong's existing API management platform.
Capabilities
Benchmark peer barsfor Long context
No task-mapped benchmark peers are available for this model yet.
Benchmark scores(1)
| Benchmark | Score | Version | Evaluation | Source |
|---|---|---|---|---|
| 1378.0 | text creative_writing 2026-10-22Observed 2026-10-22 | Configuration: Grok 4 Fast (Reasoning) Harness: LMArena blind pairwise human votes, Bradley-Terry Evaluator: LMArena Confidence: confirmed Notes: LMArena Text arena, Creative Writing category (no style control), board published 2026-10-22 (HF lmarena-ai/leaderboard-dataset @a467e6b9, text config, latest split). Board entry 'Grok 4 Fast (Reasoning)' (category creative_writing in text/latest-00000-of-00001.parquet): rank 133 of 416, rating 1378.0 (95% CI 1366.2-1389.8), 2491 votes. LLM Reference model is lifecycle-deprecated; score kept as historical. Source: LMArena (CC BY 4.0). Retrieved 2026-10-27. | Source Source: LMArena (lmarena.ai), CC BY 4.0 |
Migration checks
No linked migration route is available for this model yet.