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latestOpenAPI 3.0.0Apache 2.0 License2026-07-1497574737.9 KB

The HEAD action retrieves metadata from an object without returning the object itself. This action is useful if you're only interested in an object's metadata. To use HEAD, you must have READ access to the object.

A HEAD request has the same options as a GET action on an object. The response is identical to the GET response except that there is no response body. Because of this, if the HEAD request generates an error, it returns a generic 404 Not Found or 403 Forbidden code. It is not possible to retrieve the exact exception beyond these error codes.

If you encrypt an object by using server-side encryption with customer-provided encryption keys (SSE-C) when you store the object in Amazon S3, then when you retrieve the metadata from the object, you must use the following headers:

  • x-amz-server-side-encryption-customer-algorithm

  • x-amz-server-side-encryption-customer-key

  • x-amz-server-side-encryption-customer-key-MD5

For more information about SSE-C, see Server-Side Encryption (Using Customer-Provided Encryption Keys).

  • Encryption request headers, like x-amz-server-side-encryption, should not be sent for GET requests if your object uses server-side encryption with KMS keys (SSE-KMS) or server-side encryption with Amazon S3–managed encryption keys (SSE-S3). If your object does use these types of keys, you’ll get an HTTP 400 BadRequest error.

  • The last modified property in this case is the creation date of the object.

Request headers are limited to 8 KB in size. For more information, see Common Request Headers.

Consider the following when using request headers:

  • Consideration 1 – If both of the If-Match and If-Unmodified-Since headers are present in the request as follows:

    • If-Match condition evaluates to true, and;

    • If-Unmodified-Since condition evaluates to false;

    Then Amazon S3 returns 200 OK and the data requested.

  • Consideration 2 – If both of the If-None-Match and If-Modified-Since headers are present in the request as follows:

    • If-None-Match condition evaluates to false, and;

    • If-Modified-Since condition evaluates to true;

    Then Amazon S3 returns the 304 Not Modified response code.

For more information about conditional requests, see RFC 7232.

Permissions

You need the relevant read object (or version) permission for this operation. For more information, see Specifying Permissions in a Policy. If the object you request does not exist, the error Amazon S3 returns depends on whether you also have the s3:ListBucket permission.

  • If you have the s3:ListBucket permission on the bucket, Amazon S3 returns an HTTP status code 404 ("no such key") error.

  • If you don’t have the s3:ListBucket permission, Amazon S3 returns an HTTP status code 403 ("access denied") error.

The following actions are related to HeadObject:

head/{Bucket}/{Key}

Path parameters

Bucketstring required
<p>The name of the bucket containing the object.</p> <p>When using this action with an access point, you must direct requests to the access point hostname. The access point hostname takes the form <i>AccessPointName</i>-<i>AccountId</i>.s3-accesspoint.<i>Region</i>.amazonaws.com. When using this action with an access point through the Amazon Web Services SDKs, you provide the access point ARN in place of the bucket name. For more information about access point ARNs, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/userguide/using-access-points.html">Using access points</a> in the <i>Amazon S3 User Guide</i>.</p> <p>When using this action with Amazon S3 on Outposts, you must direct requests to the S3 on Outposts hostname. The S3 on Outposts hostname takes the form <code> <i>AccessPointName</i>-<i>AccountId</i>.<i>outpostID</i>.s3-outposts.<i>Region</i>.amazonaws.com</code>. When using this action with S3 on Outposts through the Amazon Web Services SDKs, you provide the Outposts bucket ARN in place of the bucket name. For more information about S3 on Outposts ARNs, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/userguide/S3onOutposts.html">Using Amazon S3 on Outposts</a> in the <i>Amazon S3 User Guide</i>.</p>
Keystring required

The object key.

Query parameters

versionIdstring

VersionId used to reference a specific version of the object.

partNumberinteger

Part number of the object being read. This is a positive integer between 1 and 10,000. Effectively performs a 'ranged' HEAD request for the part specified. Useful querying about the size of the part and the number of parts in this object.

Headers

If-Matchstring

Return the object only if its entity tag (ETag) is the same as the one specified; otherwise, return a 412 (precondition failed) error.

If-Modified-Sincestring date-time

Return the object only if it has been modified since the specified time; otherwise, return a 304 (not modified) error.

If-None-Matchstring

Return the object only if its entity tag (ETag) is different from the one specified; otherwise, return a 304 (not modified) error.

If-Unmodified-Sincestring date-time

Return the object only if it has not been modified since the specified time; otherwise, return a 412 (precondition failed) error.

Rangestring

Because <code>HeadObject</code> returns only the metadata for an object, this parameter has no effect.

x-amz-server-side-encryption-customer-algorithmstring

Specifies the algorithm to use to when encrypting the object (for example, AES256).

x-amz-server-side-encryption-customer-keystring password

Specifies the customer-provided encryption key for Amazon S3 to use in encrypting data. This value is used to store the object and then it is discarded; Amazon S3 does not store the encryption key. The key must be appropriate for use with the algorithm specified in the <code>x-amz-server-side-encryption-customer-algorithm</code> header.

x-amz-server-side-encryption-customer-key-MD5string

Specifies the 128-bit MD5 digest of the encryption key according to RFC 1321. Amazon S3 uses this header for a message integrity check to ensure that the encryption key was transmitted without error.

x-amz-request-payer'requester'

Confirms that the requester knows that they will be charged for the request. Bucket owners need not specify this parameter in their requests. For information about downloading objects from Requester Pays buckets, see <a href="https://docs.aws.amazon.com/AmazonS3/latest/dev/ObjectsinRequesterPaysBuckets.html">Downloading Objects in Requester Pays Buckets</a> in the <i>Amazon S3 User Guide</i>.

x-amz-expected-bucket-ownerstring

The account ID of the expected bucket owner. If the bucket is owned by a different account, the request fails with the HTTP status code <code>403 Forbidden</code> (access denied).

x-amz-checksum-mode'ENABLED'
<p>To retrieve the checksum, this parameter must be enabled.</p> <p>In addition, if you enable <code>ChecksumMode</code> and the object is encrypted with Amazon Web Services Key Management Service (Amazon Web Services KMS), you must have permission to use the <code>kms:Decrypt</code> action for the request to succeed.</p>

Response

Success