Objects and Folders


IONOS S3 Object Storage organizes data as objects. The data could range from documents, pictures, videos, backups, and other types of content. You can store these objects within the buckets and each object can be a maximum of 5 TB in size. An object consists of a key, that represents the name given to the object. This key acts like a unique identifier and you can use it to retrieve the object.

Properties and metadata

Every object uploaded to a bucket includes Object properties and Object metadata.

The properties refer to object details and the metadata are key-value pairs that store additional information about the object. The maximum size of metadata is 2 KB (keys+values). For instance, an object of type 'image' can include metadata such as its photographer, capture date, or camera used. Properly defined metadata aids in filtering and pinpointing objects using specific criteria.

Note: Currently, it is not possible to add metadata using the web console. You can add metadata using the PutObject or CreateMultipartUpload (in case of multipart upload) API calls for uploading objects.

During object storage, its properties and metadata are retrievable alongside the object.

In the web console, for any object under a bucket, the following object properties are displayed:



Defines the object (file) type such as image, pdf, zip, and so on.


The file size is shown as sequence of bytes such as MB, KB, and so on.

Modified on

The date and time when the object was last modified is displayed here.

Version ID

Represents an unique object version. If versioning for the bucket is enabled, then every object in that bucket is assigned a unique version ID. If versioning is not enabled for a bucket, then, version ID is not available for the object.

From the Object Properties page, you can also perform the following actions:

  • Download an object.

  • Copy the object URL to the clipboard.

  • Generate a Pre-Signed URL.

  • Delete an object.

Object Functions

  • Versions: Versioning objects enables the preservation, retrieval, and restoration of all versions of objects in your bucket. When versioning is enabled for a bucket, it also influences the object upload. For more information, see Versioning.

  • Access Control List (ACL): The object Access Control List (ACL) contains access control for each object defining which user accounts can read, write, or modify objects within a bucket. You can share access to a bucket and to all or specific objects in a bucket. The access permissions defined at the bucket level also influence the object access in a bucket. For more information, see Access Control List.

  • Object lock: Object lock allows you to prevent objects from being deleted or overwritten for a specified amount of time or indefinitely. It is beneficial for compliance or regulatory reasons. Currently, enabling Object lock is possible only during the bucket creation. For more information, see Object Lock.

  • Multi-part upload: Breaks down a single large object into smaller parts and uploads these objects to the bucket maximizing the upload speed. For more information, see Multi-part upload.


Folders, also known as Prefixes are containers that help to organize the objects within a bucket. You can create folders within a bucket and upload objects to folders. Object Storage offers a flat data structure instead of a hierarchy such as a file system. Hence, to support the organization of data in a well-structured way, the creation of Folders is allowed within a bucket. You can also create subfolders within a folder and upload objects to subfolders.

Emulating folders with prefixes

Unlike traditional file systems with nested folders, IONOS S3 Object Storage maintains a flat environment. There is no hierarchy of folders or directories. While the structure is flat, you can emulate folders using key naming conventions with slashes (/).

You can use prefix names that contain alphanumeric characters, dashes, and hyphens only.

Example: Instead of saving a report as Annual_Report_2023.pdf, using a key such as reports/2023/Annual_Report.pdf gives the semblance of a folder structure. These virtual folders through prefixes aid in logically grouping related objects.

Following are a few examples of using prefixes for objects to emulate folder structure:

  • user_profiles/john_doe/avatar.jpg

  • data/backups/June/backup.zip

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