Cofacts is a collaborative fact-checking system combining a LINE chatbot with a hoax database. When encountered with a message in doubt in LINE messaging app, a user can send the said message to the chatbot and get a crowd-sourced fact-checking result as a reply. Cofacts tries to tackle with mis/dis information in this closed platform using LINE’s recently-released chat bot platform. Cofacts chat bot acts like a search engine for Internet rumors but embedded right inside the messaging app, where the rumors are. This empowers people not familiar with Googling, such as senior citizens, to look for answers by themselves.