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Bilingual subtitles on every video. Click any word for an instant AI explanation. Save vocabulary and review it with spaced repetition — all without leaving the player.
No credit card · Works on Netflix, YouTube & 5 more platforms
Dual subtitles (sometimes called bilingual subtitles or bilingual captions) display the original foreign-language dialogue at the top and your native language directly below. You read the foreign line first, then glance down for instant confirmation — no pausing, no switching tabs.
Research in second-language acquisition consistently shows that comprehensible input — content you almost understand — is the most effective route to fluency. Dual subtitles keep you in that zone: challenged but never lost.
Butterfluent takes bilingual subtitles one step further. Every word in the foreign subtitle is clickable. Tap a word you don't know and get the translation, grammatical gender, tense, and an AI-generated example sentence — all inline, in under a second.
Add Butterfluent to Chrome in one click. No account required to start.
Navigate to Netflix, YouTube, Disney+, or another supported platform and press play.
Bilingual captions layer over the player. Your native language shows below each foreign line.
Tap any word for an instant AI explanation. Words save automatically for spaced-repetition review.
A full learning loop built into every video you watch.
Overlaid bilingually inside the player — no pop-ups, no overlapping UI. Works on Netflix, YouTube, Disney+, Prime, Hulu, Max, and Crunchyroll.
Tap any word in the subtitle for instant translation, grammatical gender, and a contextual AI explanation — all without pausing.
Not just the meaning — Butterfluent explains tense, case, word order, and usage patterns using Claude Haiku AI.
Save entire subtitle lines as vocabulary cards. The full sentence context is stored with each word for richer recall.
Built-in SRS flashcard system with Easy / Good / Hard scheduling. Review due words without leaving the browser.
The extension auto-pauses after each subtitle and highlights the hardest word. Active recall without any extra effort.
Butterfluent vs Language Reactor vs Trancy
| Feature | Butterfluent | Language Reactor | Trancy |
|---|---|---|---|
| Dual subtitles on Netflix | |||
| Click-to-translate words | |||
| AI grammar explanations | — | — | |
| In-panel SRS flashcards | — | — | |
| Sentence mining | — | ||
| Auto Learn Mode | — | — | |
| Retention tracking | — | — | |
| Free tier available |
Comparison based on publicly available feature lists as of 2025. Subject to change.
“The dual subtitles are actually readable — not the tiny ones that overlap everything. Loving it.”
“I tried Language Reactor but kept coming back to Butterfluent. The AI explanations make the difference.”
“Sentence mining + SRS flashcards inside the same extension is a game changer.”
Start watching with bilingual subtitles today. Upgrade when you want more.
Dual subtitles (also called bilingual subtitles) display two languages simultaneously — typically your native language below the target language. This lets you understand foreign-language content without pausing or looking words up, making it ideal for language learning.
Yes. The Butterfluent Chrome extension adds dual subtitles directly inside Netflix. Your native language appears below each line, and you can click any word for an instant AI explanation without leaving the player.
Yes. Butterfluent works on YouTube videos as well. It overlays bilingual captions in real time and lets you click any subtitle word for translation, grammar tips, and example sentences.
Butterfluent supports dual subtitles for German, French, Spanish, Italian, Portuguese, Japanese, Korean, and more. The extension automatically detects the video's language and shows your chosen native language below.
Butterfluent is free to install. The free plan includes dual subtitles, up to 30 word lookups per month, and 90 minutes of learning time. Pro users get unlimited everything for €4.99/month.