Docusign Authentication API
**Note:** This information is provided for legacy reference only. Please see our supported forms of authentication referenced below and use our [REST API Authentication Guides](https://developers.docusign.com/esign-rest-api/guides/authentication) for more information. The Authentication resource provides access to methods that allow you to authenticate user credentials and change a user's password. The methods in this resource are suitable only for [service integrations](https://developers.docusign.com/esign-rest-api/guides/common-terms) that use [Legacy Header Authentication](https://developers.docusign.com/esign-rest-api/guides/authentication/legacy). For authentication methods for [user applications](https://developers.docusign.com/esign-rest-api/guides/common-terms) and to learn more about DocuSign authentication see [Authentication Overview](https://developers.docusign.com/esign-rest-api/guides/authentication). When accessing the API resources and Legacy Header Authentication, the GET [Authentication:login method](https://developers.docusign.com/esign-rest-api/reference/Authentication/Authentication/login) allows you to determine whether a user is authenticated and provides the information you will need to make subsequent API requests.