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xAI (Grok)

The xai provider supports xAI's Grok models through an API interface compatible with OpenAI's format. The provider supports both text and vision capabilities depending on the model used.

Setup​

To use xAI's API, set the XAI_API_KEY environment variable or specify via apiKey in the configuration file.

export XAI_API_KEY=your_api_key_here

Provider Format​

The xAI provider includes support for the following model formats:

Grok-3 Models​

  • xai:grok-3-beta - Latest flagship model for enterprise tasks (131K context)
  • xai:grok-3-fast-beta - Faster variant of grok-3-beta (131K context)
  • xai:grok-3-mini-beta - Lightweight reasoning model (131K context)
  • xai:grok-3-mini-fast-beta - Faster variant of grok-3-mini with reasoning (131K context)

Grok-2 and previous Models​

  • xai:grok-2-latest - Latest Grok-2 model (131K context)
  • xai:grok-2-vision-latest - Latest Grok-2 vision model (32K context)
  • xai:grok-2-vision-1212
  • xai:grok-2-1212
  • xai:grok-beta - Beta version (131K context)
  • xai:grok-vision-beta - Vision beta version (8K context)

You can also use specific versioned models:

  • xai:grok-2-1212
  • xai:grok-2-vision-1212

Configuration​

The provider supports all OpenAI provider configuration options plus Grok-specific options. Example usage:

promptfooconfig.yaml
# yaml-language-server: $schema=https://promptfoo.dev/config-schema.json
providers:
  - id: xai:grok-3-mini-beta
    config:
      temperature: 0.7
      reasoning_effort: 'high' # Only for grok-3-mini models
      apiKey: your_api_key_here # Alternative to XAI_API_KEY

Reasoning Support​

Grok-3 introduces reasoning capabilities for specific models. The grok-3-mini-beta and grok-3-mini-fast-beta models support reasoning through the reasoning_effort parameter:

  • reasoning_effort: "low" - Minimal thinking time, using fewer tokens for quick responses
  • reasoning_effort: "high" - Maximum thinking time, leveraging more tokens for complex problems
info

Reasoning is only available for the mini variants. The standard grok-3-beta and grok-3-fast-beta models do not support reasoning.

Region Support​

You can specify a region to use a region-specific API endpoint:

providers:
  - id: xai:grok-2-latest
    config:
      region: us-west-1 # Will use https://us-west-1.api.x.ai/v1

This is equivalent to setting base_url="https://us-west-1.api.x.ai/v1" in the Python client.

Vision Support​

For models with vision capabilities, you can include images in your prompts using the same format as OpenAI. Create a prompt.yaml file:

prompt.yaml
- role: user
  content:
    - type: image_url
      image_url:
        url: '{{image_url}}'
        detail: 'high'
    - type: text
      text: '{{question}}'

Then reference it in your promptfoo config:

promptfooconfig.yaml
# yaml-language-server: $schema=https://promptfoo.dev/config-schema.json
prompts:
  - file://prompt.yaml

providers:
  - id: xai:grok-2-vision-latest

tests:
  - vars:
      image_url: 'https://example.com/image.jpg'
      question: "What's in this image?"

For more information on the available models and API usage, refer to the xAI documentation.

See Also​