> For the complete documentation index, see [llms.txt](https://postman-v1.guides.gov.sg/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://postman-v1.guides.gov.sg/email-api-guide/api-key-management/bearer-authentication.md).

# Bearer Authentication

## About Bearer Authentication

Bearer authentication (also called token authentication) is a HTTP authentication scheme that involves security tokens called bearer tokens. Note that bearer authentication should only be used over HTTPS (SSL). For more information, [see here](https://swagger.io/docs/specification/authentication/bearer-authentication/).

In the rest of this guide, we will use "API key" to refer to the bearer token used for authentication.

## Authentication Header

Postman uses bearer authentication. In practice, this means that clients calling our API should include the API key in the `Authorization` header when making requests:

```http
Authorization: Bearer <api_key>
```