I recently shipped CaptionSpark, a Chrome extension that turns browser audio into live captions.
The narrow use case is this: you are already on a page, audio is playing, and you want readable text without opening another app. That can be a video, a webinar, an X Space, a call, or a stream.
The extension starts from the active tab and puts captions over the current page. It also supports Spanish translation and keeps a transcript while the session is running.
What I learned while building it:
Caption UX is mostly about trust. People need to know when capture is active.
