This is the only comment I don't agree with. Curl sets the UA as a specific option (see https://github.com/dhensby/sapphire/blob/restfulservice-improvements/api/RestfulService.php#L204) - I also wouldn't want to put it into the default headers because the array is non-associative at the moment so this could be declared many times. Perhaps creating the headers as associative would be a good idea - but it's a big API change and out of the scope of what I'm doing or have needed to do previously.