Baidu Wangpan (百度网盘): file-sync service like Dropbox, but gives you 2TB (terrabytes!) of free storage
Tengxun Ketang (腾讯课堂): similar to edX/coursera, they have a lot of free courses on programming, machine learning, and technical topics
Wanmen Daxue (万门大学): similar to edX/coursera, they have a lot of free foreign language classes and lectures on economics/social sciences
HKGolden (香港高登): Hong Kong forum on tech and software, similar to reddit
Huxiu (虎嗅): tech news site
Toutiao Xinwen (头条新闻): news aggregator site, has categories and comments
Zhihu (知乎): QA platform, similar to Quora
Zhihu Zhuanlan (知乎专栏): blogging platform, similar to Medium
Ximalaya FM (喜马拉雅 FM): podcasts app
Duokan (多看): ebooks app similar to Kindle
Douyin (抖音): Chinese version of Tiktok
iQiyi (爱奇艺): video site with tons of movies and dramas
JD (京东): amazon-like marketplace with same-day delivery
Taobao (淘宝): ebay-like peer-to-peer marketplace
Weibo (新浪微博): microblogging site like Twitter
Zhifubao (支付宝): peer-to-peer payments app that works by scanning QR codes, very widely accepted in China
Wechat (微信): messaging app that also has tons of micro-apps and payment functionality built in