In updated terms of service released Wednesday, Twitter explicitly banned "intimate photos or videos that were taken or distributed without the subject's consent."
The update comes following Reddit's announcement last month of a similar ban, which came after the online bulletin board was criticized for allowing the distribution of hacked nude pictures of Hollywood stars.
Twitter stepped up online safety efforts last month, moving to crack down on impersonation as well as the leaking of personal, private data.
California in 2013 passed a law which specifically bars revenge porn postings.
Although legislation already existed against posting unauthorized pictures of other people which invade their privacy, the new California law covers pictures that were taken with consent, for example when a couple was together, but which are later posted online without the ex-partner's agreement.