DuetSub – Bilingual Subtitles

Official-first bilingual subtitles for Netflix, Prime Video, Max, Disney+, and YouTube.

Keep watching. Keep the original. Understand every scene. DuetSub is a free, open-source Chrome extension that places two synchronized subtitle languages on one screen. Choose any two official languages actually available for the current title, then switch, swap, or restore them without leaving the player. Why viewers choose DuetSub: - Two official tracks, one screen. Keep the original beside the language you understand instead of replacing it. - Controls where you need them. Choose the top and bottom languages, swap their positions, or reload official tracks inside the player. - Built for real playback. Subtitles stay aligned through seeking and in-player episode or video changes; disabling DuetSub restores the platform's native captions. - AI only when you ask. DuetSub contacts a compatible translation service you configure—such as DeepSeek, Qwen, or OpenAI—or a local model only when you explicitly retranslate the bottom subtitles. Translation uses scene and adjacent-cue context. Official subtitles remain the default, and DuetSub does not operate its own translation service. - Private by design. No DuetSub cloud, subscription, analytics, video download, DRM bypass, or remote code execution. Two available official tracks do not contact a translation service. Only the explicit Use AI to retranslate bottom subtitles action replaces the bottom official line; Reload official subtitles restores it. Supported players: - Netflix - Prime Video - Max at play.hbomax.com - Disney+ - YouTube creator-provided captions What's new in version 0.2.2: - Fixes Max official subtitle loading on current single-ID watch URLs and during early player startup. - Resolves duplicate Max subtitle-track ownership through the player's native selection flow; ambiguous mappings fail closed instead of guessing a subtitle URL. - Rebinds Max subtitles after in-site navigation or video replacement, while preserving native-caption restoration when DuetSub is disabled or cannot become ready. - Keeps Disney+ controls clickable when the player's gesture layer would otherwise cover them. The interface is available in English, Simplified Chinese, and Traditional Chinese. DuetSub uses only subtitle tracks available to the signed-in viewer. It does not download video, bypass DRM, unlock region-restricted tracks, execute remote code, or collect analytics. DuetSub is open source. Read the code, follow releases, or report an issue: https://github.com/semantic-craft/duetsub If DuetSub makes a show easier to understand, star the project on GitHub and help more bilingual viewers discover it. DuetSub is an independent project and is not affiliated with or endorsed by the supported streaming services.