Comprehensible Input

App profile

DuoNinja

Comprehensible-input platform combining real-world content with vocabulary review, book reading, video learning, and structured lessons.

Visit official websiteFacts last verified August 24, 2026

Best for

  • All In One Ci
  • Structured Practice
  • Book Reading
  • Vocabulary Management

Pricing

Free plan
✓Supported
Monthly
$4.99/month
Annual
$49.90/year
  • Free-plan AI credits reset daily.

Availability

Platforms

Web✓Supported
iOS✓Supported
Android✓Supported
Browser extension✓Supported
Self-hosted / local—Unsupported

Factual overview

Feature summary

Browse DuoNinja’s capabilities by category, or compare the same fields across every researched app.

Content & discovery

Built-in content library
✓Supported
Content discovery
✓Supported
News & articles
✓Supported
Books
✓Supported
YouTube / video library
✓Supported
Podcast library & discovery
—Unsupported
Import own content
✓Supported
Import webpages
—Unsupported

Reading & books

EPUB import
✓Supported
Dedicated book reader
✓Supported
Preserves original book structure
✓Supported
Preserves chapters
✓Supported
Preserves formatting
✓Supported
Preserves images
✓Supported
Text reading mode
Continuous
Book reading mode
Paginated
Book navigation / TOC
✓Supported
Reading-position sync
✓Supported
TTS / read aloud
✓Supported

Video & audio

YouTube dual subtitles
✓Supported
Netflix dual subtitles
✓Supported
Audio import
✓Supported
Automatic transcription
✓Supported
Synchronized transcript / highlighting
✓Supported

Translation & comprehension

Word translation
✓Supported
Context-aware word translation
✓Supported
Sentence translation
✓Supported
Multiple dictionaries
✓Supported
AI explanations
✓Supported
Text simplification
✓Supported
Base-form / lemma lookup
✓Supported

Vocabulary & review

Save words
✓Supported
Learning / known status
✓Supported
Separate meanings per word
✓Supported
Seen / encounter count
✓Supported
Example sentences
✓Supported
SRS flashcards
✓Supported
Multiple / custom decks
✓Supported
Vocabulary import
✓Supported
Export saved words
✓Supported
Export seen words
✓Supported
Export examples / metadata
✓Supported

Learning & guidance

Structured courses / lessons
✓Supported
Grammar roadmap
✓Supported
AI tutor
—Unsupported
Human tutors
—Unsupported
Speaking practice
Limited
Writing practice
Limited
Pronunciation practice
—Unsupported

Progress & motivation

Daily streak
✓Supported
Daily goal
✓Supported
Learner level
✓Supported
Reading statistics
✓Supported
Listening statistics
✓Supported
Achievements
—Unsupported
Leaderboards
—Unsupported

Compare DuoNinja with other apps

Context matters

Notes behind the cells

Concise cells make scanning easy. These notes preserve the important caveats from each app record.

DuoNinja

  • Text reading is continuous; book reading is paginated.
  • Sentence mode and reading audio are available.
  • The browser extension supports YouTube dual captions, but not webpage import or in-page text translation.
  • Vocabulary tools include automatic tracking, community decks, AI-generated forms, examples and images, and TTS for words and examples.
  • Duolingo vocabulary can be imported.
  • Lessons can be built manually or generated with AI.

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Alternatives to DuoNinja

LingQComprehensible-input platform built around reading and listening to a large library of real-world content and user imports.Lingo ChampionComprehensible-input platform centered on news, texts, books, videos, vocabulary tracking, and AI-assisted comprehension.Language ReactorLanguage-learning toolkit for understanding and studying native media, especially Netflix, YouTube, podcasts, books, and webpages.ReadLangWeb-based language-learning tool centered on reading, inline translation, vocabulary saving, and flashcard review.