> For the complete documentation index, see [llms.txt](https://adidas.gitbook.io/api-guidelines/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://adidas.gitbook.io/api-guidelines/rest-api-guidelines/message/message-formats.md).

# Message Formats

## Response Message Format

All **response** messages **MUST** support an [`application/hal+json`](http://stateless.co/hal_specification.html) (HAL) format.

### Error Response Format

The [`application/problem+json`](https://tools.ietf.org/html/rfc7807) (Problem Detail) **MUST** be used to communicate details about an error.

## Request Message Format

**Request** messages with body **SHOULD** support an [`application/json`](http://www.json.org) (JSON) format. Where applicable, the request message **SHOULD** also support the [`application/hal+json`](http://stateless.co/hal_specification.html) format.

**Request** messages **MAY** also support the [`application/x-www-form-urlencoded`](https://tools.ietf.org/html/rfc1866#section-8.2.1) (URL Encoded) format.