Comparison

Calibre Sync vs FSI CONNECT

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

Head to head
About

Calibre Sync

Access and manage your Calibre ebook libraries from various cloud services or wirelessly connect to your desktop. Browse, search, download, and organize your books on your device. Supports multiple libraries and accounts.

Highlights
  • Access Calibre libraries on cloud services
  • Wireless connection to Calibre
  • Supports multiple libraries and accounts
  • Browse, search, and download books
  • Organize books with filters and sorting
  • Send books to Kindle
Features
Read full description

Lifetime support, no extra charge, no subscription fee. Calibre Sync can: - help you access full Calibre libraries on most popular personal cloud services, including Google Drive, Dropbox, Microsoft OneDrive, Box, pCloud, MEGA, iCloud, WebDav, Nextcloud, OwnCloud, and TeraBox - simply the most supported for cloud services. - transform your device to a smart device emulator that connects to Calibre wirelessly. It even supports Calibre libraries on your external storage and from Calibre Content Server or Calibre-web with amazing performance. Move your Calibre libraries to your favourite cloud providers and access those libraries via Calibre Sync to browse, sort, search, download and read books on your device. Calibre Sync also supports multiple libraries across multiple Drive, Dropbox, OneDrive, Box, pCloud, MEGA, iCloud, WebDav, Nextcloud, OwnCloud, and TeraBox accounts simultaneously. Features: - Unlimited Calibre libraries - Wireless connect to Calibre effortlessly as Smart device - Easy switch between multiple libraries across multiple accounts - Automatic check and update libraries when launching the app - Pull, Refresh or Remove a library from Calibre Sync - Support different book list layouts: List - detailed and simple, Grid, and Carousel - View your library statistics - Send books to Kindle with ease - Search across all of your available libraries - Search books by title, authors, and even in comments and custom columns - Filter books on authors, series, tags, language, publishers, formats and in custom columns - Sort libraries by title, author, ratings, and several Date options - ascending and descending - Filter downloaded books - Configuration for each library download location - Support for custom columns in book details view - Quick access to book download and share via slideable list view - Zoom the book cover - Support "swipe from book to book" in book details view - Email or share a copy of downloaded book - Open downloaded book in your book reader application to read a book - View the file size of each book format - Show book identifiers and link to source (like ISBN, Amazon, Google Books, Goodreads, etc) - Dark/light themes - And many more features... To move your Calibre library to cloud services: 1) Open Calibre on your Laptop/PC/Desktop 2) Select "Switch/create library..." from the Calibre menu 3) Select an empty folder on your Cloud drive in "New Location" drop down 4) Select "Move current library to new location", then press OK 5) Wait for cloud sync to complete. 6) Then you are ready to use Calibre Sync. To move your Calibre library to your phone storage, just copy the library directory to your phone storage. Notes: - Calibre Sync is not a reader app. You must install and use one of the many excellent reader apps available. - Only Microsoft OneDrive for Personal accounts (shared) are supported. Please email us if you observe any inconsistencies. - Due to restriction in Box API, Calibre Sync must acquire write permission in order to download files, download is not a read action on Box. Calibre Sync guarantees that it will not perform any write actions against your data in Box cloud account. - Calibre Sync use WebDav API of Nextcloud and OwnCloud services, and it requires case sensitive file system to work properly. Therefore, you must make sure that your libraries are set up on case sensitive file system (Linux, recent MacOS, Windows NTFS with case sensitive enabled). Please leave your reviews and suggestions to help us improve the app. For more information see https://calibresync.bitbucket.io Calibre is © Kovid Goyal - calibre-ebook.com Drive is © Google LLC. Dropbox is © Dropbox inc. OneDrive is © Microsoft Box is © Box inc. pCloud is © pCloud AG Nextcloud is © Nextcloud GmbH OwnCloud is © OwnCloud MEGA is © MEGA iCloud is © Apple Inc TeraBox © Flextech Inc

About

FSI CONNECT

Features
Read full description

The FSI CONNECT App is a new generation of intelligent energy management application launched by Pure SAS for global users. By providing a brand-new visual experience, user-friendly data display, and more comprehensive power plant monitoring from multiple dimensions, it meets the convenient application needs of business scenarios ranging from data access to monitoring and operation maintenance.

Screenshots

Calibre Sync4 screens
FSI CONNECT4 screens

Verdict

The call

The clearest difference is price: FSI CONNECT at Free against Calibre Sync's $4.99. Calibre Sync's advantage is ads (none vs shown) and update cadence (weekly vs every 3 months). On in-app purchases, device support and iOS requirement 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

CostPrice · In-app purchases · Ads · Monetization

FSI CONNECT is free to download; Calibre Sync costs $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

UpkeepUpdate frequency

Calibre Sync ships an update weekly, FSI CONNECT every 3 months. The most recent releases landed on October 13, 2026 and September 24, 2026 respectively.

Scorecard3 real differences · 7 level
Calibre Sync versus FSI CONNECT: the parameters behind the verdict, then further details
ParameterCalibre SyncFSI CONNECT
Price$4.99Free — better
Rating3.9 (55 ratings) — better—
Positive reviews62.1% of reviews—
Number of ratings55 — better—
Update frequencyWeekly — betterEvery 3 months
AdsNo — betterYes
In-app purchasesNoNo
MonetizationPaid—
DevicesiPhone, iPad, iPod — betteriPhone, iPod
Requires iOS15.0 — better15.1
Further details — not scored
Size128 MB80 MB
Age rating4+17+
DeveloperDUONG THUY PHAMPure SAS

Bugs and requests

Calibre Sync

Reported bugs

29 issues
  • Popup reappears every launch
  • Calibre version 9 bricked the app
  • Database error
  • Stopped working since Calibre update
  • Error when changing DB
Show 24 more
  • Mega integration does not connect
  • Sync issues with Calibre v9
  • App broken since Calibre v9
  • Deprecated database columns
  • Stopped working recently
  • No longer compatible with Calibre v9
  • Sync fails
  • Failed to download metadata
  • Cannot connect to server
  • Does not work with Dropbox
  • Highlights not saved in PDF
  • Syncing new books stopped
  • Cannot use preferred mail app
  • Cannot automatically send to Kindle
  • Cannot launch preferred app from this app
  • Unable to read most book covers
  • Horrible file finding
  • Does not work on iPad after update
  • App won't find files on local storage
  • Failed to download metadata from Nutstore
  • Cannot connect to server at all
  • Cannot sync Calibre to iPad
  • WebDAV not working
  • SMB not working

Requested features

18 requests
  • More customizability with viewing options
  • Integrated ebook reader
  • Mark books as favorites
  • Calendar feature for reading
  • Use configured mail app
Show 13 more
  • Option for 'automatically send to Kindle'
  • Set preferred reading apps by type
  • Launch preferred app from this app
  • AI services for translation and text-to-speech
  • Display bookshelves
  • Update FAQ and provide YouTube tutorial
  • iCloud integration
  • Support for more cloud services
  • Ability to add book directly to cloud library
  • Mark books as read/unread and sync back
  • Support for multiple libraries
  • Local storage accessible via Files app
  • Virtual view explanation

FSI CONNECT

Not enough reviews yet to summarise bugs or requests.

In-app purchases

None

Calibre Sync

No in-app purchases

None

FSI CONNECT

No in-app purchases

Questions

Is Calibre Sync free?
Calibre Sync costs $4.99, with no in-app purchases.
Is FSI CONNECT free?
FSI CONNECT is free to download, with no in-app purchases.
Do Calibre Sync or FSI CONNECT have ads?
FSI CONNECT shows ads; Calibre Sync does not.
Which is updated more often, Calibre Sync or FSI CONNECT?
Calibre Sync ships an update weekly, and FSI CONNECT every 3 months. Most recently, Calibre Sync was updated on October 13, 2026 and FSI CONNECT on September 24, 2026.

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