> For the complete documentation index, see [llms.txt](https://developer.harness.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.harness.io/resilience-testing/chaos-engineering/faults/custom-faults/index.md).

# Overview

Custom faults allow you to extend Chaos beyond the built-in fault library to address specific testing scenarios unique to your applications and infrastructure.

{% hint style="info" %}
**NEW CHAOS STUDIO FEATURE**

**Custom Faults** are part of the enhanced **New Chaos Studio** experience. If you're an existing customer and want access to new features, contact your Harness support representative. For more details, see [New Chaos Studio Features](/resilience-testing/chaos-engineering/readme.md#new-chaos-studio-features).
{% endhint %}

## Overview <a href="#overview" id="overview"></a>

While Harness Chaos provides a comprehensive library of pre-built faults, you can create custom faults that go beyond the pre-defined fault types provided by Chaos. Custom faults enable you to tailor chaos experiments to meet specific needs, configurations, or scenarios unique to your environment.

Custom faults are ideal for:

* **Application-specific failures**: Simulate failures unique to your business logic
* **Custom infrastructure**: Target specialized infrastructure components
* **Complex scenarios**: Combine multiple failure modes in custom ways
* **Domain-specific testing**: Address industry-specific reliability requirements

## Ways to Create Custom Faults <a href="#ways-to-create-custom-faults" id="ways-to-create-custom-faults"></a>

Harness Chaos Engineering provides two approaches for creating custom faults:

### 1. Create Custom Faults <a href="#id-1-create-custom-faults" id="id-1-create-custom-faults"></a>

Build custom faults from scratch with complete control over configuration and behavior. This approach gives you maximum flexibility to implement fault injection logic tailored to your specific requirements.

[Learn more about creating custom faults →](/resilience-testing/chaos-engineering/faults/custom-faults/create-custom-faults.md)

### 2. Custom Fault Templates <a href="#id-2-custom-fault-templates" id="id-2-custom-fault-templates"></a>

Use pre-configured templates that can be customized for your specific needs. This approach provides a faster way to create faults using proven patterns and best practices.

[Learn more about custom fault templates →](/resilience-testing/chaos-engineering/faults/custom-faults/custom-fault-templates.md)