# Custom Objects

Custom Objects store arbitrary JSON-formatted data.

Custom Objects allow you to persist data that does not fit the standard data model. This frees your application from any third-party persistence solution and means that all your data stays in one place. Custom Objects are grouped into containers, which can be used like namespaces.

You can store custom data for Products and other entities in Custom Objects and access the data using [Reference Expansion](https://docs.commercetools.com/api/general-concepts.md#include-custom-data-by-expanding-custom-objects). With this approach, you can query for the custom data associated to the resource without the need for [Custom Objects scopes](https://docs.commercetools.com/api/scopes.md#custom-objects).

A maximum number of 20000000 Custom Objects can be created per Project. This is a soft limit that can be increased per Project after a performance impact review. See [Limit increase guidance](https://docs.commercetools.com/api/limit-increase-guidance.md#resource-count-limits).

## Representations

#### CustomObject

See API type definition [CustomObject](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Atype%3ACustomObject).

#### CustomObjectDraft

See API type definition [CustomObjectDraft](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Atype%3ACustomObjectDraft).

#### CustomObjectPagedQueryResponse

See API type definition [CustomObjectPagedQueryResponse](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Atype%3ACustomObjectPagedQueryResponse).

#### CustomObjectReference

See API type definition [CustomObjectReference](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Atype%3ACustomObjectReference).

#### CustomObjectKeyReference

See API type definition [CustomObjectKeyReference](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aimport%3Atype%3ACustomObjectKeyReference).

## Get CustomObject by Container and Key

See API endpoint definition [GET /\{projectKey}/custom-objects/\{container}/\{key}](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Aendpoint%3A%2F%7BprojectKey%7D%2Fcustom-objects%2F%7Bcontainer%7D%2F%7Bkey%7D%3AGET).

## Create or Update CustomObject

See API endpoint definition [POST /\{projectKey}/custom-objects](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Aendpoint%3A%2F%7BprojectKey%7D%2Fcustom-objects%3APOST).

## Query CustomObjects in Container

See API endpoint definition [GET /\{projectKey}/custom-objects/\{container}](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Aendpoint%3A%2F%7BprojectKey%7D%2Fcustom-objects%2F%7Bcontainer%7D%3AGET).

## Check if CustomObject exists

### Check if CustomObject exists by Query Predicate

See API endpoint definition [HEAD /\{projectKey}/custom-objects](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Aendpoint%3A%2F%7BprojectKey%7D%2Fcustom-objects%3AHEAD).

## Delete CustomObject by Container and Key

See API endpoint definition [DELETE /\{projectKey}/custom-objects/\{container}/\{key}](https://docs.commercetools.com/api/projects/custom-objects.md?urn=ctp%3Aapi%3Aendpoint%3A%2F%7BprojectKey%7D%2Fcustom-objects%2F%7Bcontainer%7D%2F%7Bkey%7D%3ADELETE).

## Related pages

- [Section overview page](https://docs.commercetools.com/api.md)
- [Previous page: Custom Fields](https://docs.commercetools.com/api/projects/custom-fields.md)
- [Next page: API Extensions](https://docs.commercetools.com/api/projects/api-extensions.md)