Pinyin Annotator is a free browser extension designed for Firefox that significantly enhances the learning experience for Chinese language students. It integrates pinyin annotations directly into Chinese subtitles across popular video streaming platforms, including Netflix, Disney+, YouTube, and Bilibili. This feature allows users to better understand spoken Chinese by providing phonetic guidance in real-time. The extension supports both Simplified and Traditional Chinese, making it a versatile tool for learners of various backgrounds.

In addition to its primary functionality, Pinyin Annotator offers easy accessibility, allowing users to highlight text and click the extension icon to view the pinyin without leaving the current page. It is open-source, granting users the ability to inspect the code and contribute to its development on GitHub. For added convenience, a customizable keyboard shortcut enables quick toggling of annotations, streamlining the learning process.