How do I find my API URL in Salesforce?
The API URL of Salesforce may be different.
For example, after the login in the CRM you can use the domain URL: https://eu6.salesforce.com/. However, it should look like https://eu6.salesforce.com/services/data/v31.0/ that means you use the domain URL and add services/data/v31.0/ to it.