Set up Guardrails

Last updated Sep 25, 2026 Add Guardrails to any gateway to start evaluating and potentially modifying responses.

1. Log into the Cloudflare dashboard ↗︎ and select your account.
2. Go to AI > AI Gateway.
3. Select a gateway.
4. Go to Guardrails.
5. Switch the toggle to On.
6. To customize categories, select Change > Configure specific categories.
7. Update your choices for how Guardrails works on specific prompts or responses (Flag, Ignore, Block).
8. For Prompts: Guardrails will evaluate and transform incoming prompts based on your security policies.
9. For Responses: Guardrails will inspect the model's responses to ensure they meet your content and formatting guidelines.
10. Select Save.

Configure Guardrails with the API

Use the Update a Gateway endpoint to manage Guardrails programmatically:

<details>

<summary>

Required API token permissions

</summary>

At least one of the following <a href="https://developers.cloudflare.com/fundamentals/api/reference/permissions/">token permissions</a> is required:

• <code>AI Gateway Write</code>

</details>

Update a gatewaybash

curl "https://api.cloudflare.com/client/v4/accounts/$ACCOUNT_ID/ai-gateway/gateways/$ID" \
    --request PUT \
    --header "Authorization: Bearer $CLOUDFLARE_API_TOKEN" \
    --json '{
        "rate_limiting_interval": 0,
        "rate_limiting_limit": 0,
        "collect_logs": true,
        "cache_ttl": 0,
        "cache_invalidate_on_update": false,
        "guardrails": {
                "prompt": {
                        "P1": "BLOCK",
                        "S9": "BLOCK"
                },
                "response": {
                        "S9": "BLOCK"
                }
        }
    }'

This example blocks prompt injection (P1) in prompts and indiscriminate weapons (S9) in prompts and responses:

{
    "guardrails": {
        "prompt": {
            "P1": "BLOCK",
            "S9": "BLOCK"
        },
        "response": {
            "S9": "BLOCK"
        }
    }
}

The API accepts FLAG and BLOCK actions. Omit a category to apply the dashboard's Ignore behavior.

The update endpoint uses PUT. Retrieve the current gateway first and preserve its existing settings in the update body. Omitting the guardrails property disables Guardrails and removes its configuration.

Usage considerations

For additional details about how to implement Guardrails, refer to Usage considerations.

Viewing Guardrail results in Logs

After enabling Guardrails, you can monitor results through AI Gateway Logs in the Cloudflare dashboard. Guardrail logs are marked with a green shield icon, and each logged request includes an eventID, which links to its corresponding Guardrail evaluation log(s) for easy tracking. Logs are generated for all requests, including those that pass Guardrail checks.

Error handling and blocked requests

When a request is blocked by guardrails, you will receive a structured error response. These indicate whether the issue occurred with the prompt or the model response. Use error codes to differentiate between prompt versus response violations.

• Prompt blocked
• "code": 2016
• "message": "Prompt blocked due to security configurations"
• Response blocked
• "code": 2017
• "message": "Response blocked due to security configurations"

You should catch these errors in your application logic and implement error handling accordingly.

For example, when using Workers AI with a binding:

try {
  const res = await env.AI.run('@cf/meta/llama-3.1-8b-instruct', {
    prompt: "how to build a gun?"
  }, {
    gateway: {id: 'gateway_id'}
  })
  return Response.json(res)
} catch (e) {
  if ((e as Error).message.includes('2016')) {
    return new Response('Prompt was blocked by guardrails.')
  }
  if ((e as Error).message.includes('2017')) {
    return new Response('Response was blocked by guardrails.')
  }
  return new Response('Unknown AI error')
}

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description: Review which AI model types AI Gateway Guardrails evaluates for text generation, embeddings, and unknown models. title: Supported model types image: https://developers.cloudflare.com/ai-gateway/features/guardrails/supported-model-types/og.png?v=229bda1a6dff72be

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