Grok 4.20 Non-Reasoning

Text Generation • xAI

xai/grok-4.20-0309-non-reasoning

• Third-party
• Zero data retention

xAI's Grok 4.20 non-reasoning model. Skips the thinking trace for fast, single-pass responses while keeping the same training as the reasoning variant.

Usage

const response = await env.AI.run(
  'xai/grok-4.20-0309-non-reasoning',
  { messages: [{ content: 'What are the three laws of thermodynamics?', role: 'user' }] },
)
console.log(response)

curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/v1/chat/completions \
  --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{
  "model": "xai/grok-4.20-0309-non-reasoning",
  "messages": [
    {
      "content": "What are the three laws of thermodynamics?",
      "role": "user"
    }
  ]
}'

**The Three Laws of Thermodynamics** (in their most common, concise form):

### **Zeroth Law of Thermodynamics** (often called the "zeroth" because it logically precedes the others)
> If two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.

This is the basis for the concept of **temperature** — it allows us to define a universal temperature scale.

### **First Law of Thermodynamics**
> Energy cannot be created or destroyed, only converted from one form to another.

Mathematically:  
**ΔU = Q − W**  
(where ΔU is the change in internal energy, Q is heat added to the system, and W is work done *by* the system)

This is essentially the **law of conservation of energy** applied to thermodynamic systems.

### **Second Law of Thermodynamics**
> The entropy of an isolated system always increases over time, or remains constant in ideal reversible processes. Heat flows spontaneously from hot to cold, never the reverse.

Common statements:
- "The entropy of the universe tends to a maximum."
- "It is impossible to construct a heat engine that is 100% efficient."

This law introduces the concept of **irreversibility** and the **arrow of time**.

---

### Bonus: The **Third Law of Thermodynamics** (Nernst Heat Theorem)
> As the temperature of a system approaches absolute zero (0 K), the entropy of a perfect crystal approaches a minimum (usually zero).

This implies it's impossible to reach absolute zero in a finite number of steps.

---

**Summary (popular phrasing):**
1. **Zeroth**: Temperature exists.
2. **First**: You can't win (energy is conserved).
3. **Second**: You can't break even (entropy always increases).
4. **Third**: You can't even quit the game (absolute zero is unreachable).

{
  "choices": [
    {
      "finish_reason": "stop",
      "index": 0,
      "message": {
        "content": "**The Three Laws of Thermodynamics** (in their most common, concise form):\n\n### **Zeroth Law of Thermodynamics** (often called the \"zeroth\" because it logically precedes the others)\n> If two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.\n\nThis is the basis for the concept of **temperature** — it allows us to define a universal temperature scale.\n\n### **First Law of Thermodynamics**\n> Energy cannot be created or destroyed, only converted from one form to another.\n\nMathematically:  \n**ΔU = Q − W**  \n(where ΔU is the change in internal energy, Q is heat added to the system, and W is work done *by* the system)\n\nThis is essentially the **law of conservation of energy** applied to thermodynamic systems.\n\n### **Second Law of Thermodynamics**\n> The entropy of an isolated system always increases over time, or remains constant in ideal reversible processes. Heat flows spontaneously from hot to cold, never the reverse.\n\nCommon statements:\n- \"The entropy of the universe tends to a maximum.\"\n- \"It is impossible to construct a heat engine that is 100% efficient.\"\n\nThis law introduces the concept of **irreversibility** and the **arrow of time**.\n\n---\n\n### Bonus: The **Third Law of Thermodynamics** (Nernst Heat Theorem)\n> As the temperature of a system approaches absolute zero (0 K), the entropy of a perfect crystal approaches a minimum (usually zero).\n\nThis implies it's impossible to reach absolute zero in a finite number of steps.\n\n---\n\n**Summary (popular phrasing):**\n1. **Zeroth**: Temperature exists.\n2. **First**: You can't win (energy is conserved).\n3. **Second**: You can't break even (entropy always increases).\n4. **Third**: You can't even quit the game (absolute zero is unreachable).",
        "refusal": null,
        "role": "assistant"
      }
    }
  ],
  "created": 1777675694,
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    "keySource": "Unified"
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  "system_fingerprint": "fp_bdeb03b7cd",
  "usage": {
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    "completion_tokens_details": {
      "accepted_prediction_tokens": 0,
      "audio_tokens": 0,
      "reasoning_tokens": 0,
      "rejected_prediction_tokens": 0
    },
    "cost_in_usd_ticks": 10403000,
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    "prompt_tokens": 130,
    "prompt_tokens_details": {
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Examples

<details>

<summary>With System Message — Using a system message to set context</summary>

const response = await env.AI.run(
  'xai/grok-4.20-0309-non-reasoning',
  {
    messages: [
      { content: 'You are a helpful coding assistant specializing in Python.', role: 'system' },
      { content: 'How do I read a JSON file in Python?', role: 'user' },
    ],
  },
)
console.log(response)

curl https://api.cloudflare.com/client/v4/accounts/$CLOUDFLARE_ACCOUNT_ID/ai/v1/chat/completions \
  --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
  --header "Content-Type: application/json" \
  --data '{
  "model": "xai/grok-4.20-0309-non-reasoning",
  "messages": [
    {
      "content": "You are a helpful coding assistant specializing in Python.",
      "role": "system"
    },
    {
      "content": "How do I read a JSON file in Python?",
      "role": "user"
    }
  ]
}'

``` **Reading a JSON file in Python** is very straightforward using the built-injson` module.

1. Basic Method (Recommended)

```python import json from pathlib import Path