hearsub

HearSub is a browser extension that brings real-time subtitle translation, bilingual captions, and synchronized AI dubbing straight to your YouTube viewing experience. There is no need to upload the full video or re-render anything — everything works while you watch.

As the video plays, HearSub follows the playback moment by moment, generating translated captions and natural-sounding dubbing that stay in sync with the original audio. You no longer have to pause, rewind, or copy text elsewhere just to understand foreign-language content.

The extension also detects multiple speakers in the video and preserves the original background audio, so dialogue is translated and voiced clearly while music, sound effects, and ambience remain untouched. It is a practical companion for following tutorials, lectures, interviews, and entertainment videos in any language.