---
title: Kill Switches
description: >-
  Use Boolean feature flags as kill switches to disable features instantly
  without redeploying.
breadcrumbs: Docs > Feature Flags > Use Cases > Kill Switches
---

> For the complete documentation index, see [llms.txt](https://docs.datadoghq.com/llms.txt).

# Kill Switches

{% callout %}
# Important note for users on the following Datadog sites: app.ddog-gov.com, us2.ddog-gov.com

{% alert level="danger" %}
This product is not supported for your selected [Datadog site](https://docs.datadoghq.com/getting_started/site.md). ({% placeholder "user-datadog-site-name" /%}).
{% /alert %}

{% /callout %}

A **kill switch** is a Boolean feature flag where the default state is **on** (`true`). The feature runs normally until you enact the kill switch by adding a targeting rule that serves `false`.

Use a kill switch when you need to turn off risky or broken functionality by using Datadog, without waiting for a deploy. During incidents, that gives operations and engineering a fast path to stop customer impact while the rest of the application keeps running.

## Set up a kill switch{% #set-up-a-kill-switch %}

### Step 1: Create a Boolean flag{% #step-1-create-a-boolean-flag %}

1. Navigate to [**Create Feature Flag**](https://app.datadoghq.com/feature-flags/create).

1. Set the variant type to **Boolean**.

1. Mark the flag as **Permanent**.

1. In the **Variants** section, click **Make Default** next to the **True** variant. This sets `true` as the value served to all subjects by default.

   {% image
      source="https://docs.dd-static.net/images/feature_flags/kill_switch_make_default.4863048fa5b78b6a3bac8ca56b6b75b9.png?auto=format&fit=max&w=850 1x, https://docs.dd-static.net/images/feature_flags/kill_switch_make_default.4863048fa5b78b6a3bac8ca56b6b75b9.png?auto=format&fit=max&w=850&dpr=2 2x"
      alt="The Variants section of the create flag form, showing Boolean variants with Make Default highlighted next to the True variant." /%}

1. Save the flag.

### Step 2: Evaluate the flag in your application{% #step-2-evaluate-the-flag-in-your-application %}

Wrap the feature code with a Boolean evaluation and a fallback of `true`. The fallback keeps the feature enabled if the flag configuration is unavailable:

{% tab title="JavaScript" %}

```javascript
import { OpenFeature } from '@openfeature/web-sdk';

const client = OpenFeature.getClient();
const fallback = true;
const showFeature = await client.getBooleanValue('my-kill-switch-flag', fallback);

if (showFeature) {
  // Feature code here
}
```

{% /tab %}

{% tab title="Python" %}

```python
enabled = client.get_boolean_value("my-kill-switch-flag", True, eval_ctx)
if enabled:
    # Feature code here
    pass
```

{% /tab %}

{% tab title="Go" %}

```go
enabled, _ := client.BooleanValue(ctx, "my-kill-switch-flag", true, evalCtx)
if enabled {
    // Feature code here
}
```

{% /tab %}

Deploy the application with the flag check in place before enabling the flag in production.

### Step 3: Enable the flag{% #step-3-enable-the-flag %}

Enable the flag in the target environment. No targeting rules are needed at this stage — the flag serves `true` (feature on) to all subjects by default.

### Step 4: Enact the kill switch{% #step-4-enact-the-kill-switch %}

When you need to disable the feature — for example, during a regression or to stop a third-party integration from sending requests — add a targeting rule that serves `false`:

1. Navigate to the flag in Datadog.
1. Add a targeting rule to serve `false` to the affected subjects.
1. Save the rule. The SDK serves `false` on the next configuration refresh, and the feature code path stops running for the affected subjects.

## Best practices{% #best-practices %}

- Use a fallback of `true` so the feature stays enabled if the flag is unavailable — you don't want the feature to accidentally turn off due to a connectivity issue.
- Mark the flag as **Permanent**. Kill switches are intended to be long-lived, and marking them permanent prevents them from being flagged as [stale](https://docs.datadoghq.com/feature_flags/concepts/stale_flags.md).
- Test the kill switch in staging before relying on it in production.
- Use evaluation tracking to confirm the flag state during an incident.

## Further reading{% #further-reading %}

Additional helpful documentation, links, and articles:

- [Client-Side SDKs](https://docs.datadoghq.com/feature_flags/client.md)