The structure of URLs for the API is: https://api.whatismybrowser.com/api/v3/end-point
The request structure varies by endpoint but the general idea is that if you're POST-ing something for us to process (eg. all your visitor's HTTP Headers for us to Detect their system), you'll send the POST body as valid JSON and we'll take it from there.
To get the latest version numbers, it will be a GET request.
Check the documentation for the end point in question.
Each API request needs to be Authenticated, read the section on Authentication for more information.
Continue reading: Common Response elements.