# xAI: Grok 4 Fast (free): AI model fact sheet

- **Provider:** xai
- **Released:** 2025-09-19
- **Context window:** 2,000,000 tokens
- **Parameters:** Not disclosed
- **API pricing:** $0.000 / 1M input, $0.000 / 1M output
- **OpenRouter ID:** x-ai/grok-4-fast:free
- **Capabilities:** conversation, analysis, code-generation

Grok 4 Fast is xAI's latest multimodal model with SOTA cost-efficiency and a 2M token context window. It comes in two flavors: non-reasoning and reasoning. Reasoning can be enabled via the API.

## Benchmarks

| Benchmark | Score |
| --- | --- |
| SWE-bench | 75.0% |

Source: real side-by-side outputs, pricing and specs at https://rival.tips/models/grok-4-fast-free