The Entrenue API follows the REST specification and all calls are made using GET or POST requests to the specified endpoints. See here for more information about REST:
Wikipedia.
All calls can be made by using cURL or the HTTP tools which come with any standard web programming language. For the purposes of the documentation, we will be showing calls made using cURL on the command line, but you can make the same calls using PHP, Java, Ruby, etc. More information about cURL can be found here:
Wikipedia.