Anybody know what I am doing wrong here? API Login doesn't seem to work if I specify format=xml, but does work with the default (html) format. I *am* using the POST method. The username and password contain no odd characters so it almost certainly isn't a urlencoding problem. I have also tried this with Wikimedia Commons login with the same result. The following is a shell session using the lynx browser to illustrate the problem. Sensitive data has been blanked out. The second browser invocation is identical to the first except for "&format=xml", but instead of returning xml it returns only blank lines. tony@home:~$ lynx -post-data http://en-wikipedia.org/w/api.php action=login&lgname=USERNAME&lgpassword=PASSWORD --- You are looking at the HTML representation of the XML format. HTML is good for debugging, but probably is not suitable for your application. See [1]complete documentation, or [2]API help for more information. <?xml version="1.0"?> <api> <login result="Success" lguserid="XXX" lgusername="USERNAME" lgtoken="TOKEN" cookieprefix="enwiki" sessionid="SESSIONID" /> </api> References 1. http://www.mediawiki.org/wiki/API 2. http://en.wikipedia.org/w/api.php tony@home:~$ lynx -post-data http://en-wikipedia.org/w/api.php action=login&lgname=USERNAME&lgpassword=PASSWORD&format=xml --- tony@home:~$