CaptionSpark: Browser Audio Captions

Live captions and transcripts for browser audio: videos, X Spaces, calls, streams, with Spanish translation.

Watch the demo video to see CaptionSpark turn browser audio into readable live captions. CaptionSpark adds a compact live caption overlay to web pages so long videos, X Spaces, calls, streams, and spoken browser audio are easier to follow. Start captions from the extension icon or keyboard shortcut, then read a focused transcript overlay while the conversation continues. CaptionSpark is built for sustained listening: small readable text, subtle speaker indicators, more surrounding context, and optional Spanish translation. Features: - Live subtitles/captions for microphone, tab, or supported page audio. - Compact transcript view that shows more conversation at once. - Speaker-aware indicators when speaker data is available. - Optional Spanish translation for caption text. - Free tier with 5 caption minutes. - Paid tier: add 120 caption minutes through Stripe Checkout for $1.19. - Caption minutes are prepaid usage, not a subscription. Privacy and billing: - Audio is processed only while captions are active. - Stripe handles card payments; CaptionSpark does not see card details. - Billing validation and API keys run through the CaptionSpark bridge, not inside the extension package.