Understand any YouTube video in your language
PolyTube builds a full, unlimited transcript and translates videos into your language with AI — with no cap on the number of videos. Bilingual subtitles overlay right on the player, with a click-to-seek transcript sidebar.
Free · Unlimited videos · Many languages supported
Everything you need to understand foreign videos
Built for real viewers — unlimited, fast, and privacy-respecting.
Unlimited full transcript
Generates a complete transcript for any video, no matter how long. Click any line to jump there; the active line highlights green and auto-scrolls.
Understand videos in your language
AI translates the video into your language as you watch — with no cap on the number of videos. Just sign in and go, no setup required.
Bilingual subtitle overlay
Translated captions appear large and clear on the video, the original line small and dimmed above. Adapts to YouTube light/dark theme.
Smart windowed translation
Translates progressively around the playhead and prefetches as you go — smooth, with no waiting for the whole video.
Glossary terms
Pin fixed translations for names and technical terms so the output stays consistent across the whole video.
Export SRT / TXT
Download captions in three modes: translated-only, original-only, or dual. Filename follows the video title.
Extra: bring your own LLM (BYO)
Want full control? Enable BYO mode to use your own API key with Anthropic, OpenRouter, DeepSeek, Groq, or a custom endpoint. The key stays in your browser and is sent only to the provider you pick — no server in between.
Flexible: use it out of the box, or bring your own LLM
Use it right away with unlimited videos — or enable BYO mode to use the LLM provider you love.
BYO mode supports custom OpenAI-compatible endpoints too.
Get started in 3 steps
Install the extension
Add PolyTube from the Chrome Web Store and pin it to your toolbar.
Sign in & pick a language
Sign in to translate unlimited videos, then pick your target language. (Want your own LLM? Enable BYO mode in Options.)
Open a video & hit Translate
Go to any YouTube video and click Translate on the overlay. The transcript and bilingual subtitles appear within seconds.
Hotkeys
Customize at chrome://extensions/shortcuts
- Alt+Shift+TToggle subtitle overlay
- Alt+Shift+SToggle transcript sidebar
- Alt+Shift+RReplay the last few seconds
Privacy first
- Two modes: the PolyTube backend translates (default) or use your own API key (BYO).
- In BYO mode your API key stays in your browser and goes straight to the provider you pick.
- Sign-in is optional; no ads and no third-party trackers.
- Runs on HTTPS YouTube only — blocks MITM injection of spoofed captions.
Frequently asked questions
Yes. The extension is free and translates an unlimited number of videos once you sign in. If you prefer, you can enable BYO mode to use your own LLM API key.
Ready to watch YouTube without a language barrier?
Install PolyTube and translate your first video in minutes.