In another example of potential data sharing between TikTok and ByteDance, Patrick Spaulding Ryan, who was TikTok’s lead technical program manager for security engineering until 2022, and another former TikTok U.S.-based employee, cited some of the company’s internal software systems that they said were maintained and monitored by China-based ByteDance teams. Lark, a Slack-like internal messaging system that ByteDance and TikTok share, is among the most important shared software systems used by the two businesses, say the former employees. Because Lark is run by ByteDance, ByteDance workers could see discussions by TikTok employees, including ones about U.S. user data.