// model_detail
legacy fast
Grok 4 Fast
by xAI
Previous-generation fast Grok. 2M context. Superseded by Grok 4.1 Fast.
Context window 2M 2M tokens
Max output 32K 32K tokens
Pricing /1M tok $0.20 in / $0.50 out per 1M tokens (API)
Released Sep 1, 2025
// specifications
Specs & capabilities
API details
- API model ID
grok-4-fast- Internal ID
grok-4-fast- Status
- legacy
- Type
- fast
Capabilities
- Vision
- 👁️ Yes
- Function calling
- 🔧 Yes
Pricing
- Input
- $0.20 / 1M tokens
- Output
- $0.50 / 1M tokens
- Source
- First-party API pricing
Lifecycle
- Predecessor
- Grok 4.1 Fast
- Successor
- Grok 4.1 Fast
// data_confidence
Data notes
⚠️ Knowledge cutoff not listed
// notes
Additional notes
Previous fast variant
// more_from_xai
More xAI models
Grok 4.20 active frontier
xAI's newest flagship with industry-leading speed and agentic tool calling. 2M context, lowest hallucination rate.
Grok 4.20 Multi-Agent active frontier
Variant of Grok 4.20 for collaborative agent-based workflows. Multiple agents operate in parallel.
Grok 4.1 Fast active fast
Fast non-reasoning variant. 2M context. Cost leader among frontier-class providers.
Grok Code Fast 1 active coding
xAI's coding-focused model. 256K context, optimized for code generation.
Grok 4 legacy frontier
Previous-generation Grok flagship. 256K context. Superseded by Grok 4.20.
Grok 3 Mini legacy fast
Smaller Grok 3 variant with reasoning. 131K context. Cost-efficient.
// external_links