QQ

QQ is Tencent's long-running messenger, predating WeChat by more than a decade, and it remains widely used — particularly among younger users, gaming communities and for work that involves moving files.

Its strengths are group features and file transfer: large groups with fine-grained management, group file storage, and transfer of big files without the size limits that constrain most messengers. For many Chinese teams and communities it fills the role Discord or Slack plays elsewhere.

It also carries a desktop client with a full feature set, which is one reason it persists alongside WeChat rather than being replaced by it.