With XML/JSON

You can authenticate as follows only using an administrator privileges.

http://yourservername:portnumber/psa/api.do?function=login&username=username&password=password&company-code=company code

If data format is XML and your authentication is successful, you will receive XML with two elements: token and user_id. For example:

<result>
   <token>a1dc42fb-d420-10feb-aaks9-89f5c0e8sk3c</token>
   <user_id>112233</user_id>
</result>

In case the data format is JSON, you will receive an object with properties token and user_id respectively.

{"result":{"token":"a1dc42fb-d420-10feb-aaks9-89f5c0e8sk3c","user_id":112233}}

On how to handle errors, see Error Handling and Debugging