SyncBooks! vs KeyReader
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
SyncBooks!
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SyncBooks! is a multilingual ebook reader that unlocks the “depth” of classic literature with cutting-edge technology. It’s more than just reading – it’s listening, comparing, and learning. Experience public domain masterpieces in a more profound way. 【Key Features】 ・Sentence-by-Sentence Audio Sync Synchronizes text and audio on a sentence-by-sentence basis. The current reading location is highlighted in real-time, allowing you to follow along with both your eyes and ears. ・Multilingual Parallel Display Equipped with high-quality translations powered by LLM. Freely switch between the main and sub languages for a display tailored to your learning style. ・Two Reading Modes Read-Along Mode: An active reading experience synchronized with audio. Novel Mode: A focused reading experience with minimal distractions. ・Audio System Includes recorded narration for original English texts, and utilizes device’s text-to-speech for translated versions, ensuring seamless listening. ・Dictionary Integration Simply tap a word to display the iOS standard dictionary. Check meanings without interrupting your reading flow. ・Public Domain Works Features a curated collection of classic literature with a design optimized for comfortable reading. 【About the Translation】 The translation for this app was generated by AI (LLM). It may contain inaccuracies or unnatural phrasing depending on the context. Please use it as an aid to understanding the original text. 【Recommended for】 ・Those who want to learn a language through literature. ・Those who want to efficiently engage in extensive and intensive reading. ・Those who want to deepen their understanding by comparing original texts and translations. ・Those who want to build a collection of classic works.
KeyReader
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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/
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Verdict
The clearest difference is in-app purchases: SyncBooks! at none against KeyReader's 3. KeyReader's advantage is iOS requirement (18.0 vs 26.0). On price, ads and device support there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. KeyReader sells 3 in-app purchases, starting at $2.99 per month. SyncBooks! asks for nothing beyond the download.
| Parameter | SyncBooks! | KeyReader |
|---|---|---|
| Price | Free | Free |
| Update frequency | — | Every 3 weeks |
| Ads | No | No |
| In-app purchases | No — better | Yes |
| Devices | iPhone, iPad — better | iPhone |
| Requires iOS | 26.0 | 18.0 — better |
| Further details — not scored | ||
| Size | 16 MB | 7 MB |
| Age rating | 4+ | 4+ |
| Developer | koji ozono | Oleg Strigunov |
In-app purchases
SyncBooks!
No in-app purchases
KeyReader
- Unlimited Reading$2.991 Month
- Unlimited Reading3 Days trial$19.991 Year
- Unlimited Reading$49.99





