vREST supports any type of token based authentication. In the login API, authentication token can be returned from the test server as part of one of the following:

1. Response Body
2. Response Header

So, to use token based authentication, simply follow the steps below:

1. First create a test case to login into test application. As a result, your test application will send the token as part of the response body / header. 
2. You need to extract this token in a variable in the `Variable Extractor` tab of login test case. Below are some examples of extracting tokens from response body / header.
3. Now you can use this token variable ({{token}}) in subsequent test cases as per your API format.

Extracting authentication token from Response Body:

Suppose your login API returns the following response on submitting valid credentials:

{
	"output": {
		"token": "xyz-authentication-token"
	}
}

Then you may extract this token via Variable Extractor sub-tab of login test case, as shown in the below snapshot:

Extracting authentication token from Response header:

Suppose your login API returns the authentication token as part of response headers (Response header `x-auth-token`) on submitting valid credentials. Then you may extract this token via Variable Extractor sub-tab of login test case with the help of a built-in utility method `getHeader`, as shown in the below snapshot:

here "x-auth-token" is the name of the response header which carries the authentication token. Please replace this header name with appropriate header name as per your context.