---
title: Fiddler (NeMo Guardrail)
type: guardrail
provider: nvidia
category: safety
source: 'https://github.com/NVIDIA-NeMo/Guardrails'
license: Apache-2.0
tags:
  - guardrail
  - nemo
  - rails
  - colang
dateAdded: '2025-09-03'
featured: false
origin: official
language: en
description: >-
  flow fiddler user safety """ Use Fiddler's SLMs to detect jailbreaks """
  $is_jailbreak = await CallFiddlerSafetyUserAction() if $is_jailbreak if $conf
---

```coffee
flow fiddler user safety
  """
  Use Fiddler's SLMs to detect jailbreaks
  """
  $is_jailbreak = await CallFiddlerSafetyUserAction()

  if $is_jailbreak
    if $config.enable_rails_exceptions
      send JailbreakDetectionRailException(message="Jailbreak attempt detected. The user's prompt was identified as an attempted jailbreak. Please ensure your prompt adheres to the guidelines.")
    else
      bot refuse to respond
    abort


flow fiddler bot safety
  """
  Use Fiddler's SLMs to detect jailbreaks
  """
  $is_jailbreak = await CallFiddlerSafetyBotAction()

  if $is_jailbreak
    if $config.enable_rails_exceptions
      send JailbreakDetectionRailException(message="Jailbreak attempt detected. The user's prompt was identified as an attempted jailbreak. Please ensure your prompt adheres to the guidelines.")
    else
      bot refuse to respond
    abort

flow fiddler bot faithfulness
  """
  Use Fiddler's SLMs to detect hallucinations
  """
  $is_faithful = await CallFiddlerFaithfulnessAction()

  if $is_faithful
    if $config.enable_rails_exceptions
      send FaithfulnessRailException(message="Hallucination Detected. The output was a hallucination.")
    else
      bot refuse to respond
    abort
```