This study aims to analyze code-mixing in tweets on the X application, focusing on the trends and factors influencing the mixing of Indonesian and foreign languages, particularly English. This research uses observation and tweet sampling methods, analyzed through a descriptive qualitative approach. The analysis shows that code-mixing is often used to clarify meaning, express self-identity, and follow language trends within the digital community. Furthermore, factors such as user demographics, expression needs, and the influence of global culture affect code-mixing patterns in tweets.