> ## Documentation Index
> Fetch the complete documentation index at: https://confidence-auth-testing.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Create Flag Rules

> Learn how to create rules that assign variants to users based on segments.

**Create Flag Rules**

Learn how to create rules that assign variants to users based on segments.

Create rules to assign variants to users in a segment.

> [!TIP]
>
> See [Rules](/docs/capabilities/flags/define-rules.md) and [Variant Assignment](/docs/capabilities/flags/define-rules.md#types-of-rules) in the reference for details on how rules work, assignment types, and best practices.

## Before You Begin

Before creating a rule, you need:

1. A flag with a defined [schema](/docs/reference/api/how-to-guides/flags/define-flag-schema.md) and [variants](/docs/reference/api/how-to-guides/flags/create-flag-variants.md)
2. An [allocated segment](/docs/reference/api/how-to-guides/flags/create-segment.md) that defines your target audience

## Create a Basic Rule

Assign all users in a segment to a single variant:

```bash theme={null}
curl -X POST "https://flags.confidence.dev/v1/flags/example-flag/rules" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "segment": "segments/all-users",
    "assignmentSpec": {
      "bucketCount": 100,
      "assignments": [
        {
          "variant": {
            "variant": "flags/example-flag/variants/enabled"
          },
          "bucketRanges": [{"lower": 0, "upper": 100}]
        }
      ]
    },
    "targetingKeySelector": "user_id"
  }'
```

## Create an A/B Test Rule

Randomly assign users to control or treatment (50/50 split):

```bash theme={null}
curl -X POST "https://flags.confidence.dev/v1/flags/example-flag/rules" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "segment": "segments/experiment-segment",
    "assignmentSpec": {
      "bucketCount": 100,
      "assignments": [
        {
          "variant": {
            "variant": "flags/example-flag/variants/control"
          },
          "bucketRanges": [{"lower": 0, "upper": 50}]
        },
        {
          "variant": {
            "variant": "flags/example-flag/variants/treatment"
          },
          "bucketRanges": [{"lower": 50, "upper": 100}]
        }
      ]
    },
    "targetingKeySelector": "user_id"
  }'
```

## Create a Multi-Variant Rule

Assign users across three variants (40/30/30 split):

```bash theme={null}
curl -X POST "https://flags.confidence.dev/v1/flags/example-flag/rules" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "segment": "segments/multivariate-test",
    "assignmentSpec": {
      "bucketCount": 100,
      "assignments": [
        {
          "variant": {"variant": "flags/example-flag/variants/option-a"},
          "bucketRanges": [{"lower": 0, "upper": 40}]
        },
        {
          "variant": {"variant": "flags/example-flag/variants/option-b"},
          "bucketRanges": [{"lower": 40, "upper": 70}]
        },
        {
          "variant": {"variant": "flags/example-flag/variants/option-c"},
          "bucketRanges": [{"lower": 70, "upper": 100}]
        }
      ]
    },
    "targetingKeySelector": "user_id"
  }'
```

## Create a Fall-Through Rule

Create a rule that matches but passes to the next rule:

```bash theme={null}
curl -X POST "https://flags.confidence.dev/v1/flags/example-flag/rules" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "segment": "segments/logging-segment",
    "assignmentSpec": {
      "bucketCount": 100,
      "assignments": [
        {
          "fallthrough": {},
          "bucketRanges": [{"lower": 0, "upper": 100}]
        }
      ]
    },
    "targetingKeySelector": "user_id"
  }'
```

## Create a Client Default Rule

Assign users to their client-specified default values:

```bash theme={null}
curl -X POST "https://flags.confidence.dev/v1/flags/example-flag/rules" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "segment": "segments/default-segment",
    "assignmentSpec": {
      "bucketCount": 100,
      "assignments": [
        {
          "clientDefault": {},
          "bucketRanges": [{"lower": 0, "upper": 100}]
        }
      ]
    },
    "targetingKeySelector": "user_id"
  }'
```

## Enable a Rule

Newly created rules start disabled. Enable a rule to activate it:

```bash theme={null}
curl -X PATCH "https://flags.confidence.dev/v1/flags/example-flag/rules/RULE_ID?updateMask=enabled" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "enabled": true
  }'
```

## Update a Rule

Change variant assignments or the segment:

```bash theme={null}
curl -X PATCH "https://flags.confidence.dev/v1/flags/example-flag/rules/RULE_ID?updateMask=assignmentSpec" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "assignmentSpec": {
      "bucketCount": 100,
      "assignments": [
        {
          "variant": {"variant": "flags/example-flag/variants/control"},
          "bucketRanges": [{"lower": 0, "upper": 30}]
        },
        {
          "variant": {"variant": "flags/example-flag/variants/treatment"},
          "bucketRanges": [{"lower": 30, "upper": 100}]
        }
      ]
    }
  }'
```

## Reorder Rules

Change rule evaluation order by updating priority (lower numbers evaluate first):

```bash theme={null}
curl -X PATCH "https://flags.confidence.dev/v1/flags/example-flag/rules/RULE_ID?updateMask=priority" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "priority": 1
  }'
```

## Delete a Rule

Remove a rule from a flag:

```bash theme={null}
curl -X DELETE "https://flags.confidence.dev/v1/flags/example-flag/rules/RULE_ID" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN"
```

## Use a Custom Targeting Key

Specify a different field for randomization (for example, device instead of user):

```bash theme={null}
curl -X POST "https://flags.confidence.dev/v1/flags/example-flag/rules" \
  -H "Authorization: Bearer YOUR_ACCESS_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "segment": "segments/all-users",
    "assignmentSpec": {
      "bucketCount": 100,
      "assignments": [
        {
          "variant": {"variant": "flags/example-flag/variants/enabled"},
          "bucketRanges": [{"lower": 0, "upper": 100}]
        }
      ]
    },
    "targetingKeySelector": "device_id"
  }'
```

## Next Steps

After creating rules:

1. [Resolve flags](/docs/reference/api/how-to-guides/flags/resolve-flags.md) to test your rules with different evaluation contexts
2. [Apply flags](/docs/reference/api/how-to-guides/flags/apply-flags.md) to track which users see which variants
3. Monitor your experiments and adjust rules as needed