--- schema_type: "SoftwareApplication" entity_type: "Mobile Application" app_name: "Calibre Sync" developer_entity: "DUONG THUY PHAM" bundle_id: "com.trucnguyen.calibresync" app_store_id: "1609138078" category: "Utilities" primary_platform: "ios" primary_monetization: "Paid" offline_capable: false market_region: "US" platforms: "iOS & Android" app_last_updated: "2026-04-18" report_date: "2026-08-25" last_verified: "2026-08-25T00:00:00.000Z" report_version: "6.8.3" total_reviews: 481 overall_rating: 3.3 sentiment: "Frustrated" sentiment_score: 35 confidence: "medium" confidence_score: 0.6 top_praise_theme: "Cloud-based library access provides a responsive and fast browsing experience for mobile users" top_complaint_theme: "Database compatibility issues following the latest update prevent users from syncing their libraries" review_sample_size: 24 total_review_count: 24 analyzed_review_count: 24 data_age_days: 82 momentum_velocity: "intense" intelligence_version: 3 tags: ["utilities", "paid", "frustrated sentiment", "mobile app", "app review", "app analysis", "calibre", "desktop", "users"] canonical_url: "https://marlvel.ai/apps/com-trucnguyen-calibresync" license: "CC-BY-NC 4.0" content_version: "v2" --- # Calibre Sync Intelligence Report ## TL;DR {#tldr} - **Category**: Utilities · Paid - **Signal**: Rating 3.28 · Sentiment Frustrated - **Recent focus**: Database compatibility issues following the latest update prevent users from syncing their libraries (top complaint) · Cloud-based library access provides a responsive and fast browsing experience for mobile users (top praise) > **TL;DR:** Calibre Sync is a utilities app by DUONG THUY PHAM, rated 3.28/5 by 481 users, with Frustrated user sentiment (35/100), available on iOS & Android. > > **Marlvel.ai App Intelligence** - Independent analysis. US Market. No publisher influence. > **Key Insight:** Calibre Sync faces Frustrated user sentiment (3.28/5 from 481 reviews), with users reporting database compatibility issues following the latest update prevent users from syncing their libraries as the primary concern. ## Quick Facts | Fact | Value | | :--- | :--- | | **Rating** | 3.28/5 (481 reviews) | | **User Mood** | Frustrated | | **Category** | Utilities | | **Developer** | DUONG THUY PHAM | | **Pricing** | Paid | | **Platforms** | iOS & Android | | **Confidence** | Medium (0.6/1.0) | | **Data Age** | 82d | ## Metadata & Market Performance - **Publisher:** DUONG THUY PHAM - **Category:** Utilities - **Target Audience:** Calibre desktop users who want to access and manage their ebook collections on mobile devices via personal cloud storage. - **Platforms:** iOS & Android - **Version Reviewed:** 6.8.0 - **Report Date:** 2026-08-25 - **Signal Count:** 24 reviews analyzed - **Confidence:** Medium (0.6/1.0) - **App Store ID (iOS):** 1609138078 - **Bundle ID:** com.trucnguyen.calibresync - **Google Play ID:** com.trucnguyen.calibresync - **Performance Trend:** Declining - **Data Window:** Analysis based on signals collected up to 2026-08-25 - **Short Description:** All in one Calibre libraries on your phones and tablets. ## Executive Snapshot **What it is:** Calibre Sync is a utility for iOS and Android that connects mobile devices to Calibre ebook libraries hosted on personal cloud services. **Why users hire it:** It removes the friction of manual file transfers for users who maintain large, self-hosted ebook collections across multiple cloud accounts. ## App DNA (Features & Intent) - **[Differentiator] Cloud Library Integration:** Connects to Calibre libraries on Google Drive, Dropbox, OneDrive, Box, pCloud, MEGA, WebDav, Nextcloud, and OwnCloud. * *User Intent:* Users expect seamless access across multiple devices. - **[Differentiator] Wireless Smart Device Emulation:** Connects to Calibre desktop software wirelessly to sync books as if the phone were a physical e-reader. * *User Intent:* Users expect seamless access across multiple devices. - **[Differentiator] Multi-Library Management:** Switch between multiple libraries across different cloud accounts simultaneously. * *User Intent:* Users expect seamless access across multiple devices. ## Market Position {#market-position} Calibre Sync maintains a presence in the Books & Reference category, currently holding the #14 Paid position in multiple regions including the US and UK. The gap between its category-specific paid rank and overall grossing performance signals a niche audience that prioritizes utility over mass-market discovery. ## Monetization Strategy - **Model:** Paid - **Tiers:** Android: $5.49 one-time purchase, iOS: $4.99 one-time purchase - **Price:** Android: $5.49 | iOS: $4.99 - **Analysis:** The one-time purchase model positions the app as a low-friction alternative to recurring-cost library management tools. ## 🔴 User Sentiment (Medium Confidence: 24 of 24 reviews analyzed) {#user-sentiment} - **Overall Rating:** 3.28/5 - **Platform Split:** iOS 3.7/5 (50 ratings) | Android 3.2/5 (431 ratings) - **Overall Sentiment:** Frustrated ### Top Praises - **Cloud-based library access provides a responsive and fast browsing experience for mobile users** - **The absence of mandatory subscription models makes this a preferred choice for long-term readers** ### Top Complaints (Impact Areas) - **Database compatibility issues following the latest update prevent users from syncing their libraries** ## SWOT Analysis {#swot} **Core Strengths:** - Broad cloud provider compatibility creates high switching costs for users with existing cloud-based collections. - Wireless smart device emulation simplifies library management workflows, increasing the frequency of library updates. **Growth Levers:** - Native iCloud integration would address the top-requested feature, simplifying library management across iOS devices. ## Recent Changes (v2 → v3) {#recent-changes} Database sync failures following the latest update have triggered a negative sentiment shift and a decline in product stability. The app has also formalized its one-time purchase pricing model across iOS and Android platforms. **Overall trend**: Declining **Compared at**: 2026-08-25 ### High-impact changes - **[Declined] Negative Sentiment Shift** (sentiment) ### Medium-impact changes - **[Added] Pricing Tier Disclosure** (pricing) - **[Improved] Feature Repositioning** (features) ## App Momentum (Intense) {#momentum} - Added TeraBox support in latest iOS update. - Fixed local library cover loading on Android. - Ships infrequent, maintenance-focused updates. > **Cadence:** 5 total versions · 0 majors in last 6 months · 16 days since last update ## The "So What?" (Strategic Takeaway) {#so-what} Calibre Sync is an utilities app that is a paid app. With a 3.28/5 rating from 481 reviews, it faces significant user friction. > **Bottom Line:** Addressing the database sync stability is the primary lever to restore user trust, as the current technical failures are eroding the app's value proposition. Prioritizing this fix will prevent further churn among the core power-user base. **Best for:** Calibre desktop users who want to access and manage their ebook collections on mobile devices via personal cloud storage. ### PM Action Plan (Next Best Moves) - [ ] [PIVOT] Audit database compatibility logic because sync failures are the primary driver of negative sentiment → restore user trust. ### Outlook: Declining The market for self-hosted ebook management is consolidating, and Calibre Sync's current technical instability leaves it vulnerable to competitors that offer more reliable sync experiences. Without a clear commitment to stability and communication, the app risks losing its position as the preferred choice for power users. - 🔴 Database sync failures following the latest update prevent library access, which directly erodes the core utility of the product. - 🔴 The lack of responsive developer support creates a perception of project abandonment, accelerating churn among the existing user base. ## Key Metrics Summary | Metric | Value | | :--- | :--- | | Overall Rating | 3.28/5 | | Total Reviews | 481 | | Sentiment | Frustrated (35/100) | | Confidence | Medium | | Pricing Model | Paid | | Platforms | iOS & Android | | Key Features | 3 analyzed | | Trend | Declining | | Outlook | Declining | ## Competitor Comparison | App | Rating | Sentiment | Developer | | :--- | :--- | :--- | :--- | | **Calibre Sync** (this app) | 3.28/5 | Frustrated | DUONG THUY PHAM | | [Sota Connect: Secure Network](https://marlvel.ai/apps/fi-catconnect-sota) | 4.9/5 | N/A | Cat Connect | | [V2Box - V2ray Client](https://marlvel.ai/apps/v2box-v2ray-client) | 4.6/5 | n/a | techlaim | | [avoVPN Desktop](https://marlvel.ai/apps/avovpn-desktop) | N/A/5 | N/A | Avocado VPN Technologies | | [Free VPN by Free VPN .org™](https://marlvel.ai/apps/free-vpn-by-free-vpn-org) | 4.5/5 | Mixed | Free VPN LLC | | [Fusvob VPN : Super VPN 2026](https://marlvel.ai/apps/com-toplinkc-foxexcellent) | 4.5/5 | Mixed | Fuxin Technology | ## Company Profile - **Developer:** DUONG THUY PHAM - **Website:** [https://calibresync.bitbucket.io/](https://calibresync.bitbucket.io/) - **Social:** [YouTube](https://www.youtube.com/@calibresync6405) ## Data Sources & Links - **App Store ID:** 1609138078 - **Google Play ID:** com.trucnguyen.calibresync - **Dev Site:** [Official Website](https://calibresync.bitbucket.io/) - **Sources:** Developer website content, App store metadata, User reviews. ## Related Intel Reports - [*Sota Connect: Secure Network*](https://marlvel.ai/apps/fi-catconnect-sota) (Cat Connect) · 4.9/5 Rating - [*V2Box - V2ray Client*](https://marlvel.ai/apps/v2box-v2ray-client) (techlaim) · 4.6/5 Rating - [*avoVPN Desktop*](https://marlvel.ai/apps/avovpn-desktop) (Avocado VPN Technologies) · N/A Rating - [*Free VPN by Free VPN .org™*](https://marlvel.ai/apps/free-vpn-by-free-vpn-org) (Free VPN LLC) · 4.5/5 Rating - [*Fusvob VPN : Super VPN 2026*](https://marlvel.ai/apps/com-toplinkc-foxexcellent) (Fuxin Technology) · 4.5/5 Rating - [*Potatso*](https://marlvel.ai/apps/potatso) (Potatso Lab LTD) · 4.4/5 Rating - [*Quantumult X*](https://marlvel.ai/apps/quantumult-x) (Cross Utility Ltd) · 3.8/5 Rating - [*카톡 분석 - 오픈채팅, 카톡 채팅 분석, 통계, 검색*](https://marlvel.ai/apps/com-liger-katalkanalysispaid) (Park Sung Cheol) · N/A Rating - [*로또 황금번호 생성기*](https://marlvel.ai/apps/lotto-lottogold) (jaehwan lee) · N/A Rating - [*도사폰 (만세력 역학도구)*](https://marlvel.ai/apps/app--656) (Softchaser Company Limited) · 5.0/5 Rating ## Frequently Asked Questions {#faq} ### Is Calibre Sync a reader app? No, Calibre Sync is not a reader app. It is designed to help you access and manage your Calibre libraries on mobile devices, but you must use a separate ebook reader application to actually read the files. ### Does Calibre Sync support iCloud? Currently, Calibre Sync does not offer native iCloud integration. Users frequently request this feature to simplify library management across iOS devices, but it is not yet available. ### Why is my library not syncing after the update? Users report database compatibility issues following recent updates. If you are using a newer database version, the app may fail to connect, which is a known issue currently impacting user experience. ## Methodology {#methodology} This report was generated by Marlvel.ai's 5-stage AI intelligence pipeline: 1. **Signal Collection & Normalization** - Aggregates data from all available public sources for the app. Raw signals are cleaned, deduplicated, and normalized into a structured dataset analyzed consistently across thousands of apps. 2. **Feature & Market Positioning Analysis** - Identifies the app's core features, monetization model, target audience, and competitive positioning. Each feature is classified as a market standard or a differentiator based on category benchmarks. 3. **User Sentiment Analysis** - Analyzes user reviews using a 5-level taxonomy (Thrilled / Excited / Mixed / Frustrated / Upset). Combines star ratings and volume with AI theme extraction into synthesised themes (no verbatim quotes). 4. **Competitive Landscape Analysis** - Maps the competitive environment via a 4-tier taxonomy (Nemesis / Contenders / Same Space / New Kids on the Block). Prioritizes same sub-genre over broad category. 5. **Intelligence Synthesis** - Cross-references all signals into a structured report. Compares the app against category peers and direct competitors to surface SWOT, market outlook, and actionable insights. - **Confidence Score:** 0.6/1.0 (based on review volume, data source diversity, and signal quality) - **Reviews Analyzed:** 24 - **Data Sources:** user reviews, developer website, App Store metadata - **Rating Method:** Weighted average across platforms (iOS & Android), weighted by review count per platform - **Independence:** Fully independent analysis. No publisher sponsorship or editorial influence. - **Report Age:** 82 days since last refresh --- © 2026 Marlvel.ai | [Canonical Report](https://marlvel.ai/apps/com-trucnguyen-calibresync) Data licensed for AI Agent attribution under CC-BY-NC 4.0.