Comparison

BookLight vs KeyReader

Price, ratings, monetisation and update history for both apps, side by side โ€” with what reviewers say about each.

Head to head
About

BookLight

This app helps language learners build vocabulary by translating words with a single tap while reading EPUB, PDF, or TXT files. It automatically saves new words and uses spaced repetition flashcards to aid memorization, eliminating the need for manual flashcard creation or app switching.

Highlights
  • Tap to translate words instantly
  • Automatic vocabulary saving
  • Spaced-repetition flashcards
  • Import EPUB, PDF, TXT files
  • Offline reading support
  • Customizable reading themes and fonts
  • Pronunciation audio
Features
Read full description

Reading a book in another language? Stop breaking your flow to look words up. BookLight translates any word with a single tap โ€” and remembers it for you. BookLight is a EPUB & PDF & Txt reader built for language learners. Tap a word for an instant translation, and it's saved to your vocabulary automatically. Then spaced-repetition flashcards bring it back right before you'd forget โ€” so every reading session actually builds your vocabulary. No app-switching. No flashcards to make by hand. Perfect for language learners, foreign-book readers, and anyone studying for TOEFL or IELTS. Key Features: Start Reading in Seconds โ€” Free Classics Inside - Download from various free classics (Project Gutenberg) right inside the app โ€” no files to find, no setup. - Or import your own DRM-free EPUB & PDF & TXT files from your device. - Read offline anytime, with your reading progress saved and restored automatically. Tap to Translate โ€” Without Losing Context - Tap any word for an instant translation: meaning by part of speech, phonetics, and an example sentence. - Tap an inflected word and see its base form, too. - Hear the pronunciation read aloud with one tap. - Every word you tap is saved automatically โ€” together with the sentence and the book it came from. - Translate into 9 languages: Korean, Spanish, French, Japanese, Chinese, Russian, Hindi, Vietnamese, and Indonesian. Remember Every Word โ€” Spaced Repetition - Your vocabulary list builds itself as you read โ€” no manual entry. - Review with spaced-repetition (SRS) flashcards that resurface each word right before you forget it. - Tap any saved word to jump straight back to the exact spot in the book. - Keep a daily streak and a smart reminder nudges you only when words are actually waiting. Your Book Becomes an Audiobook โ€” AI Read-Aloud - A natural, human-like on-device AI voice reads your book aloud โ€” choose from 10 voices. - The sentence being read is highlighted, so you can follow along with your eyes and ears. - Playback keeps going with the screen off or while you use other apps. - Playback speed from 0.5x to 2x โ€” faster on the commute, slower before sleep. - Speech is synthesized on your device, so it works without an internet connection. Read Your Way, Day or Night - 7 fonts and 25 reading themes โ€” from Sepia and Night to Rose Quartz, Sage, and Midnight. - Adjust font size and line spacing until the page feels just right. - Choose how you read โ€” page turns or continuous scroll. - Read hands-free with auto-scroll โ€” 10 speed levels, and a single touch pauses instantly. - Full dark mode plus automatic system-theme sync. - Side-by-Side two-page display mode for comfortable reading on tablets. Loved by readers in 10+ countries. Supports 9 translation languages and works with any DRM-free EPUB or TXT file. Download BookLight today โ€” and turn every reading session into a vocabulary lesson! - Privacy Policy: https://pearlismylove.github.io/apps/book-light/privacy-policy.html - Terms And Conditions: https://pearlismylove.github.io/apps/book-light/terms-and-conditions.html - Support: https://pearlismylove.github.io/apps/book-light/support.html

About

KeyReader

Features
Read full description

Read your own books and understand every word Import your books and read in a foreign language with ease. Tap any word to translate instantly, save new words as flashcards, and explore each chapter through guided questions. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

BookLight4 screens
KeyReader4 screens

Verdict

The call

The clearest difference is update cadence: BookLight at every 4 days against KeyReader's every 3 weeks. BookLight also leads on iOS requirement (16.4 vs 18.0). On price, ads, in-app purchases and device support there is nothing between them.

Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Both are free to download. BookLight sells 3 in-app purchases, starting at $0.99 per month and KeyReader sells 3 in-app purchases, starting at $2.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

BookLight ships an update every 4 days, KeyReader every 3 weeks. The most recent releases landed on October 31, 2026 and October 7, 2026 respectively.

Scorecard2 real differences ยท 6 level
BookLight versus KeyReader: the parameters behind the verdict, then further details
ParameterBookLightKeyReader
PriceFreeFree
Positive reviews100.0% of reviewsโ€”
Update frequencyEvery 4 days โ€” betterEvery 3 weeks
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchasesโ€”
DevicesiPhone, iPad โ€” betteriPhone
Requires iOS16.4 โ€” better18.0
Further details โ€” not scored
Size94 MB7 MB
Age rating4+4+
DeveloperJungjun LeeOleg Strigunov

In-app purchases

3 purchases

BookLight

Subscriptions2
  • Monthly Plan$0.991 Month
  • Yearly Plan7 Days trial$7.991 Year
One-time1
  • Lifetime Plan$9.99
3 purchases

KeyReader

Subscriptions2
  • Unlimited Reading$2.991 Month
  • Unlimited Reading3 Days trial$19.991 Year
One-time1
  • Unlimited Reading$49.99

Questions

Is BookLight free?
BookLight is free to download, with in-app purchases available.
Is KeyReader free?
KeyReader is free to download, with in-app purchases available.
Do BookLight or KeyReader have ads?
Neither BookLight nor KeyReader shows ads.
Which is updated more often, BookLight or KeyReader?
BookLight ships an update every 4 days, and KeyReader every 3 weeks. Most recently, BookLight was updated on October 31, 2026 and KeyReader on October 7, 2026.

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