The U.S. app Clubhouse erupted among Chinese social-media users over the weekend, with thousands joining discussions on contentious subjects such as Taiwan and Xinjiang undisturbed by Beijing’s censors.

On the invite-only, audio-based social app where users host informal conversations, Chinese-speaking communities from around the world gathered to discuss China-Taiwan relations and the prospects of unification, and to share their knowledge and experience of Beijing’s crackdown on Muslim Uighurs in the far west region of Xinjiang.

Open discussion of such topics is off limits in China, where heavy government censorship is the norm. Unfavorable comments or articles are rapidly removed on platforms such as Tencent Holdings Ltd.’s WeChat and Sina Corp.’s microblogging platform Weibo.