# ListFaces
<a name="API_ListFaces"></a>

Returns metadata for faces in the specified collection. This metadata includes information such as the bounding box coordinates, the confidence (that the bounding box contains a face), and face ID. For an example, see [Listing faces in a collection](https://docs.aws.amazon.com/rekognition/latest/dg/list-faces-in-collection-procedure.html). 

This operation requires permissions to perform the `rekognition:ListFaces` action.

## Request Syntax
<a name="API_ListFaces_RequestSyntax"></a>

```
{
   "CollectionId": "string",
   "FaceIds": [ "string" ],
   "MaxResults": number,
   "NextToken": "string",
   "UserId": "string"
}
```

## Request Parameters
<a name="API_ListFaces_RequestParameters"></a>

For information about the parameters that are common to all actions, see [Common Parameters](CommonParameters.md).

The request accepts the following data in JSON format.

 ** [CollectionId](#API_ListFaces_RequestSyntax) **   <a name="rekognition-ListFaces-request-CollectionId"></a>
ID of the collection from which to list the faces.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 255.  
Pattern: `[a-zA-Z0-9_.\-]+`   
Required: Yes

 ** [FaceIds](#API_ListFaces_RequestSyntax) **   <a name="rekognition-ListFaces-request-FaceIds"></a>
An array of face IDs to filter results with when listing faces in a collection.  
Type: Array of strings  
Array Members: Minimum number of 1 item. Maximum number of 4096 items.  
Pattern: `[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}`   
Required: No

 ** [MaxResults](#API_ListFaces_RequestSyntax) **   <a name="rekognition-ListFaces-request-MaxResults"></a>
Maximum number of faces to return.  
Type: Integer  
Valid Range: Minimum value of 0. Maximum value of 4096.  
Required: No

 ** [NextToken](#API_ListFaces_RequestSyntax) **   <a name="rekognition-ListFaces-request-NextToken"></a>
If the previous response was incomplete (because there is more data to retrieve), Amazon Rekognition returns a pagination token in the response. You can use this pagination token to retrieve the next set of faces.  
Type: String  
Length Constraints: Maximum length of 255.  
Required: No

 ** [UserId](#API_ListFaces_RequestSyntax) **   <a name="rekognition-ListFaces-request-UserId"></a>
An array of user IDs to filter results with when listing faces in a collection.  
Type: String  
Length Constraints: Minimum length of 1. Maximum length of 128.  
Pattern: `[a-zA-Z0-9_.\-:]+`   
Required: No

## Response Syntax
<a name="API_ListFaces_ResponseSyntax"></a>

```
{
   "FaceModelVersion": "string",
   "Faces": [ 
      { 
         "BoundingBox": { 
            "Height": number,
            "Left": number,
            "Top": number,
            "Width": number
         },
         "Confidence": number,
         "ExternalImageId": "string",
         "FaceId": "string",
         "ImageId": "string",
         "IndexFacesModelVersion": "string",
         "UserId": "string"
      }
   ],
   "NextToken": "string"
}
```

## Response Elements
<a name="API_ListFaces_ResponseElements"></a>

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

 ** [FaceModelVersion](#API_ListFaces_ResponseSyntax) **   <a name="rekognition-ListFaces-response-FaceModelVersion"></a>
Version number of the face detection model associated with the input collection (`CollectionId`).  
Type: String

 ** [Faces](#API_ListFaces_ResponseSyntax) **   <a name="rekognition-ListFaces-response-Faces"></a>
An array of `Face` objects.   
Type: Array of [Face](API_Face.md) objects

 ** [NextToken](#API_ListFaces_ResponseSyntax) **   <a name="rekognition-ListFaces-response-NextToken"></a>
If the response is truncated, Amazon Rekognition returns this token that you can use in the subsequent request to retrieve the next set of faces.  
Type: String

## Errors
<a name="API_ListFaces_Errors"></a>

For information about the errors that are common to all actions, see [Common Error Types](CommonErrors.md).

 ** AccessDeniedException **   
You are not authorized to perform the action.  
HTTP Status Code: 400

 ** InternalServerError **   
Amazon Rekognition experienced a service issue. Try your call again.  
HTTP Status Code: 500

 ** InvalidPaginationTokenException **   
Pagination token in the request is not valid.  
HTTP Status Code: 400

 ** InvalidParameterException **   
Input parameter violated a constraint. Validate your parameter before calling the API operation again.  
HTTP Status Code: 400

 ** ProvisionedThroughputExceededException **   
The number of requests exceeded your throughput limit. If you want to increase this limit, contact Amazon Rekognition.  
HTTP Status Code: 400

 ** ResourceNotFoundException **   
The resource specified in the request cannot be found.  
HTTP Status Code: 400

 ** ThrottlingException **   
Amazon Rekognition is temporarily unable to process the request. Try your call again.  
HTTP Status Code: 500

## See Also
<a name="API_ListFaces_SeeAlso"></a>

For more information about using this API in one of the language-specific AWS SDKs, see the following:
+  [AWS Command Line Interface V2](https://docs.aws.amazon.com/goto/cli2/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for .NET V4](https://docs.aws.amazon.com/goto/DotNetSDKV4/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for C\$1\$1](https://docs.aws.amazon.com/goto/SdkForCpp/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for Go v2](https://docs.aws.amazon.com/goto/SdkForGoV2/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for Java V2](https://docs.aws.amazon.com/goto/SdkForJavaV2/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for JavaScript V3](https://docs.aws.amazon.com/goto/SdkForJavaScriptV3/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for Kotlin](https://docs.aws.amazon.com/goto/SdkForKotlin/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for PHP V3](https://docs.aws.amazon.com/goto/SdkForPHPV3/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for Python](https://docs.aws.amazon.com/goto/boto3/rekognition-2016-06-27/ListFaces) 
+  [AWS SDK for Ruby V3](https://docs.aws.amazon.com/goto/SdkForRubyV3/rekognition-2016-06-27/ListFaces)