DualCap
Install
Free Chrome Extension

Learn any language through the shows you already love.

DualCap puts live bilingual captions on Netflix, YouTube, and more — with grammar breakdowns, word lookup, and a personal dictionary. No app switching. Just watch and absorb.

Add to Chrome — it's freeSee how it works

Free forever · Requires a free Groq API key · No account needed

DualCap showing bilingual captions and grammar breakdown on a video
Works onNetflixYouTubeDisney+Prime VideoHuluMaxMubiCrunchyroll
How it works

Up and running in 3 steps

No backend, no account, no friction. Your data stays in your browser.

01

Install DualCap

Add it to Chrome from the Web Store in one click. No account, no sign-up required.

02

Add your free Groq API key

DualCap uses Groq's AI for translation and grammar. Get a free key at console.groq.com — no credit card needed. Paste it into Settings inside the extension.

03

Open a video and turn on subtitles

Go to YouTube or Netflix, turn on subtitles in the player, and DualCap instantly shows both lines — original on top, translated below. Click any word to look it up. Click the translation for a full grammar breakdown.

Features

Everything you need to actually learn

No other extension combines live captions, grammar AI, and a personal dictionary.

Bilingual captions, live

Core

Original and translated subtitles side by side, directly on the video. Draggable, resizable, works in fullscreen. No delay — translations arrive in under 100ms.

DualCap extension panel showing bilingual captions

Grammar breakdowns — A2 to C2

AI-powered

Click the translated caption and the video pauses. A panel shows tense, sentence structure, word-by-word roles, CEFR difficulty level, a key insight, and example sentences using the same pattern.

Word lookup on tap

Dictionary

Tap any word in the captions. Get the definition, pronunciation, part of speech, grammatical gender (crucial for German, French, Spanish), and two example sentences. Instantly.

Personal dictionary

Learning

Save any caption with one tap. DualCap automatically fetches the meaning and stores it with the original, translation, definition, and examples. Browse, search, and download your dictionary as a PDF.

Loop mode

Practice

Press L to loop the current sentence. The best technique for training your ear and practising pronunciation — used by polyglots worldwide.

Works where you watch

Compatibility

Netflix · YouTube · Disney+ · Amazon Prime Video · Hulu · Max · Mubi · Crunchyroll

In action

Watch and learn. No switching tabs.

Click any translated line. The video pauses. A full grammar breakdown appears — tense, word roles, CEFR level, key insight.

DualCap showing grammar breakdown overlay on a Netflix video in fullscreen
Grammar panel— Tense · CEFR · Word roles
Side panel— All captions live
Bilingual overlay— EN + DE on screen
“

Built by a designer learning German through Netflix.

I was watching German series to learn the language — immersion works, but every tool I tried was either expensive, clunky, or both. So I built my own.

DualCap started as a weekend project. Now it's a full learning system — translation, grammar, dictionary, all inside the browser while you watch. No app switching, no subscriptions, no friction.

A
Abhishek Jha
Designer & product builder · uxabhi.com · @uxabhi_
Guides

Getting started

Step-by-step instructions for everything you need.

How to get your free Groq API key

DualCap uses Groq's AI for translations and grammar explanations. Groq offers a generous free tier — no credit card required.

  1. 1Go to console.groq.com and create a free account.
  2. 2Click "API Keys" in the left sidebar, then click "Create API Key". Give it any name (e.g. "DualCap").
  3. 3Copy the key — it starts with gsk_.
  4. 4Open DualCap in Chrome → click the icon in your toolbar → click "Settings" → paste your key in the API Key field → click Save.

That's it. You're ready to start.

How to use DualCap on YouTube

  1. 1Open any YouTube video.
  2. 2Click the CC button in the video player to enable captions.
  3. 3DualCap automatically detects the subtitle language and shows both lines.
  4. 4Change languages anytime from the side panel (click the DualCap icon → Side panel).
Tip: Press C on YouTube to quickly toggle captions on and off.

How to use DualCap on Netflix

  1. 1Open any Netflix show or movie.
  2. 2Click the dialogue icon in the Netflix player and choose a subtitle language.
  3. 3DualCap overlays the translation above the native subtitles.
  4. 4Click any translated line to pause and read the grammar breakdown.
Note: Choose a subtitle language different from your target learning language for best results. For example, if you're learning German, watch a German show with German subtitles and translate to English.

How to build your personal dictionary

  1. 1Watch any video with DualCap running.
  2. 2When a sentence appears that you want to remember — click Save to dictionary.
  3. 3DualCap automatically fetches the definition, part of speech, gender, and examples.
  4. 4Open the Dictionary tab in the side panel to browse all saved entries.
  5. 5Click ↓ PDF to download your full dictionary as a formatted document.
FAQ

Common questions

Is DualCap free?
Yes. The extension is free. You need a Groq API key for translations — Groq's free tier is generous and doesn't require a credit card.
Does it work on Netflix?
Yes. Enable subtitles in the Netflix player first, then DualCap translates them in real time.
Which languages are supported?
Any language Netflix or YouTube has subtitles for. Translation supports: English, German, French, Spanish, Italian, Portuguese, Dutch, Polish, Russian, Japanese, Chinese, Korean, Arabic, Hindi, Turkish, Swedish, Ukrainian, Vietnamese, and more.
Does DualCap collect any data?
No. DualCap does not track you, collect browsing history, or store anything outside your browser. Subtitle text is sent to Groq's API for translation only. See the Privacy Policy for full details.
Why do I need a Groq API key?
Groq powers the AI translation and grammar explanations. Rather than build a backend (which would require accounts and subscriptions), DualCap lets you use your own free key directly — faster, cheaper, and more private.
Does it work in fullscreen?
Yes. The overlay moves into the fullscreen container automatically.
Can I export my saved vocabulary?
Yes. Open the Dictionary tab in the side panel and click ↓ PDF. You'll get a formatted document with all your saved words, definitions, and examples.

Still have questions? Reach out directly.

hello@uxabhi.com