DeepLingo

About

DeepLingo turns the time you already spend on YouTube and Netflix into French vocabulary practice. While you watch, the extension overlays clickable subtitles over the player. Click any word to see its translation, IPA pronunciation, examples, and inflection — then save it with one click.

WHAT YOU GET

• Click-to-translate subtitles on YouTube and Netflix. The native player captions are hidden so you only see DeepLingo's interactive overlay. Click any word for an instant lookup.

• Save words with or without an account. Saved words live on this browser by default, so you can start using DeepLingo immediately. Sign in at deeplingo.ca to sync them across devices and back them up — the extension prompts you once to upload your local saves on first sign-in.

• Saved-word fade. Words you've already saved appear faded in the overlay so your eye is naturally drawn to new vocabulary.

• Transcript sidebar (press T or click the ▤ icon). Browse every caption captured so far, search across them, jump to any line on YouTube, see saved words inline with their translations, and download the transcript as text or CSV.

• Vocabulary export. Download your saved words as CSV (for Anki, Quizlet, spreadsheets) or plain text — with or without translations and source info. Export works whether you're signed in or not.

• Offline-friendly translation fallback. When a word isn't in our bundled French dictionary, Chrome's built-in on-device translator (Chrome 138+) fills the gap with no extra round trip and no extra data sent anywhere.

PRIVACY

We are very deliberate about what leaves your device:

• We do not collect subtitle text. Captions stay in your browser.
• We do not collect the URLs of pages you visit.
• We do not log clicks, scrolls, focus, or any other behavioral data by default. Anonymous usage telemetry and crash reports are both opt-in (default OFF) and toggleable in Options.
• The only data sent to our backend is what you explicitly save to your DeepLingo vocabulary — and only after you sign in and choose to sync. Each entry is the French word, its translation, an optional source (show + timestamp), and the example sentence.

Full policy: https://deeplingo.ca/privacy/extension

HOW IT WORKS

1. Open any French YouTube or Netflix video and turn on French captions.
2. Click any word in the subtitle for a translation popup.
3. Click "+ Add to vocabulary" to save it (stays on this browser).
4. Optional: sign in at deeplingo.ca to sync saved words across devices.
5. Open the transcript sidebar (T) for full-episode browsing.

SUPPORTED SITES

• YouTube (any video with French captions, including auto-generated)
• Netflix (any title with a French subtitle track)

Works only with your own subscriptions. We never modify, scrape, or bypass any platform's content-protection mechanisms.

TECHNICAL NOTES

• Manifest V3 service worker, modern Chrome only (latest two versions supported).
• Built with Preact, ~25 KB main overlay bundle, runs entirely in the user's browser.

LIMITATIONS

• French → English only in v1.
• Some Netflix titles deliver subtitles only as bitmap images; those cannot be intercepted and DeepLingo will simply not appear.
• Click-to-seek from the sidebar works on YouTube; on Netflix, seeks initiated outside Netflix's own player trigger an "M7375" error, so this feature is hidden there.

WHAT'S NEXT

Sentence translation, dual subtitles, and Prime Video support are planned for v1.2.