Version: 5.1.1
Client Credentials
With this approach, you make a POST Request with a base64 encoded string (consists of ClientId + ClientSecret). You will directly get the token (Without a local HTTP Server), but it will expire and can't be refreshed. If you want to use it securely, you would need to do it all server-side. NOTE: You will only be able to query non-user-related information e.g search for a Track.
More info: here