There are two women. One posted on Twitter the next day boasting about the awesome night she'd had with Assange. She later deleted the post but others had recorded it already. The other woman sent lots of text messages saying she wasn't raped and only reported Assange because she wanted him to take an std test, that the police had blown it up and seemed to want to get him.
http://mobile.abc.net.au/news/2016-12-07/julian-assange-goes...
Moreover the women only filed these charges after they met each other and realised they'd both slept with him.
Look, I don't know why you're being so skeptical about this. False reports of rape are extremely common. Most credible studies I've seen peg it at 50% or higher. You should never take such an accusation at face value before a case has been won and in this case we don't even need a trial - the women both created documentary evidence they were lying and one even attempted to destroy it.