I just tried to query the article API for the following URL:
http://www.foxnews.com/imag/Food/5+New+Greens+to+Power+Up+Your+Salad
The + characters were converted to spaces internally somehow and I got a 404 error from the diffbot server.
you can URLEncode the url parameter
Check out how the AJAX requests is sent when you submit that URL on the demo page: http://www.diffbot.com/docs/api/article
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