### Get a single feature flag by key

By default, this returns the configurations for all environments. You can filter environments with the `env` query parameter. For example, setting `env=production` restricts the returned configurations to just the `production` environment.

#### Recommended use

This endpoint can return a large amount of information. Specifying one or multiple environments with the `env` parameter can decrease response time and overall payload size. We recommend using this parameter to return only the environments relevant to your query.

### Expanding response

LaunchDarkly supports the `expand` query param to include additional fields in the response, with the following fields:

- `evaluation` includes evaluation information within returned environments, including which context kinds the flag has been evaluated for in the past 30 days
- `migrationSettings` includes migration settings information within the flag and within returned environments. These settings are only included for migration flags, that is, where `purpose` is `migration`.

For example, `expand=evaluation` includes the `evaluation` field in the response.

### Authentication

- **Authorization**: API Key authentication via header

### Path parameters

- **projectKey**  (string) Required `format: "string"`  
  The project key
- **featureFlagKey**  (string) Required `format: "string"`  
  The feature flag key

### Query parameters

- **env** (string) Optional `format: "string"`  
  Filter configurations by environment
- **expand** (string) Optional `format: "string"`  
  A comma-separated list of fields to expand in the response. Supported fields are explained above.

### Response

#### Global flag response
- **name** (string)  
  A human-friendly name for the feature flag
- **kind** (enum)  
  Kind of feature flag  
  Allowed values: boolean, multivariate
- **key** (string)  
  A unique key used to reference the flag in your code
- **_version** (integer)  
  Version of the feature flag
- **creationDate** (long)  
  Timestamp of flag creation date
- **variations** (list of objects)  
  An array of possible variations for the flag
  - **temporary** (boolean)  
    Whether the flag is a temporary flag
  - **tags** (list of strings)  
    Tags for the feature flag
- **_links** (map from strings to objects)  
  The location and content type of related resources

#### Experimentation data for the feature flag
- **experiments** (object)
- **customProperties** (map from strings to objects)  
  Metadata attached to the feature flag
- **archived** (boolean)  
  Boolean indicating if the feature flag is archived
- **description** (string) Optional  
  Description of the feature flag
- **clientSideAvailability** (object) Optional  
  Which type of client-side SDKs the feature flag is available to
- **maintainerId** (string) Optional  
  Associated maintainerId for the feature flag
- **_maintainer** (object) Optional  
  Associated maintainer member info for the feature flag
- **maintainerTeamKey** (string) Optional  
  The key of the associated team that maintains this feature flag
- **archivedDate** (long) Optional  
  If archived is true, date of archive
- **deprecated** (boolean) Optional  
  Boolean indicating if the feature flag is deprecated
- **defaults** (object) Optional  
  The indices, from the array of variations, for the variations to serve by default
- **migrationSettings** (object) Optional  
  Migration-related settings for the flag
- **stale** (object) Optional  
  Information about a flag's stale states
- **environments** (map from strings to objects) Optional  
  Details on the environments for this flag.

### Errors
- **401** Unauthorized Error
- **403** Forbidden Error
- **404** Not Found Error
- **429** Too Many Requests Error