Why Your Book Tracker Needs to Sync Across All Your Devices

You're reading on your iPad on the couch. Later, you want to check your reading goal on your iPhone. Or maybe you track a quick reading session on your phone during lunch, then want to see your statistics on your Mac at home.

This should be simple. Your book tracking app should sync seamlessly across all your devices. But for many popular book trackers, it doesn't work that way.

The lack of cross-device sync is one of the most frustrating limitations in book tracking apps — and one of the most common reasons readers switch to alternatives.

The Problem with Single-Device Trackers

Bookly: The Prime Example

Bookly is a popular reading app with excellent features: reading timer, statistics, goal tracking, a nice interface. But it has one fatal flaw: no cross-device sync.

Your books, your reading time, your statistics — all trapped on the one device where you recorded them.

The consequences:

Fragmented data: If you read on your iPad sometimes and your iPhone sometimes, you have two incomplete libraries.

Lost investment: Switch phones? Your reading history is gone unless you manually back up and restore.

No big picture: Your statistics only show partial data. Your "books read this year" count is split across devices.

Inconsistent progress: Update progress on one device, it doesn't appear on others. Your currently reading book shows different progress everywhere.

This isn't a minor inconvenience — it makes the app fundamentally broken for how most people actually use devices.

Why Apps Skip Sync

Sync is hard to build properly:

Technical complexity: Syncing data across devices requires server infrastructure, conflict resolution, offline handling, and constant maintenance.

Cost: Servers cost money. Sync infrastructure requires ongoing operational expense.

Development time: Building reliable sync can take months of engineering work.

For many indie developers, these costs aren't justified by the potential revenue. So they ship single-device apps and hope users don't mind.

Users mind.

How Modern Readers Actually Use Devices

The single-device assumption is outdated. Here's how readers actually behave:

Multiple Reading Devices

Many readers have:

• iPhone for reading on the go
• iPad for reading at home
• Mac for quick reference or statistics
• Maybe even multiple phones (personal/work)

Each device is optimal for different contexts. Expecting readers to only ever use one device ignores reality.

Context-Dependent Device Choice

On the couch: iPad On the bus: iPhone At a coffee shop: Either Quick session at work: iPhone Deep reading weekend: iPad Checking statistics: Whatever's nearby

Reading happens across devices because life happens across devices.

The Phone-Upgrade Problem

Even if you only use one device, you'll eventually upgrade. Without sync:

• Set up your new phone
• Download your reading app
• All your history is gone
• Start over from scratch

This is unacceptable for an app designed to track years of reading history.

What Good Sync Looks Like

Seamless and Automatic

Sync should just work. You shouldn't:

• Manually trigger sync
• Wait for sync to complete
• See conflicts you need to resolve
• Think about sync at all

Add a book on your iPhone, open your iPad, the book is there. That's the expectation.

Offline-Capable

Good sync works without constant connectivity:

• Record reading sessions offline
• Add books offline
• Make updates offline
• Sync catches up when you're online again

Internet shouldn't be required for basic functionality.

Fast and Reliable

Sync should be:

• Near-instant when online
• Reliable (no lost data)
• Consistent (same data everywhere)
• Conflict-free (automatic resolution)

Privacy-Respecting

Sync requires storing data somewhere. The question is where:

Company servers: Your data lives on their infrastructure. They potentially have access.

Your personal cloud: Data lives in your iCloud (or equivalent). Company has no access.

The second option — using your own cloud account — provides sync without sacrificing privacy.

iCloud Sync: The Apple Approach

For Apple device users, iCloud sync offers the best of both worlds:

How It Works

Apps can use CloudKit, Apple's cloud database, to sync data across your devices. Here's what happens:

1. You add a book on your iPhone
2. It's saved locally AND to your iCloud account
3. Your iPad sees the iCloud change
4. The book appears on your iPad

All through your personal iCloud storage.

Privacy Architecture

With CloudKit Private Database:

• Data is stored in your iCloud, not the app developer's servers
• Encrypted with keys only you possess
• App developers cannot access your data
• Same protection as your photos, notes, and messages

This is fundamentally different from apps that sync through their own servers.

Reliability

iCloud sync is maintained by Apple. It:

• Works across all Apple devices
• Handles offline gracefully
• Resolves conflicts automatically
• Has Apple's uptime and reliability

Indie developers don't need to maintain sync infrastructure — Apple handles it.

Evaluating Sync in Book Trackers

When choosing a book tracker, ask:

Does it sync at all?

Some apps don't sync. Period. Your data exists on one device only. This is a dealbreaker for most modern users.

What devices does it support?

Some apps sync between phones only, or between limited device types. Make sure your devices are covered.

Where does synced data live?

• On the company's servers? (Privacy exposure)
• In your personal cloud account? (Private)
• Both? (Understand what goes where)

How fast is sync?

Test it: make a change on one device, see how quickly it appears on another. Seconds is acceptable. Minutes is annoying. Hours is broken.

Does it work offline?

Can you add books and track reading without internet? What happens when you reconnect? Offline capability matters for real-world usage.

What happens during device setup?

Set up a new device. Is your reading history there? This is the ultimate sync test.

The Competition Landscape

Goodreads

Sync: Yes, via their servers Privacy: All data goes through Amazon's infrastructure Verdict: Syncs well but with privacy trade-offs

StoryGraph

Sync: Yes, via their servers Privacy: Data stored on company servers Verdict: Works but depends on company's cloud

Hardcover

Sync: Yes, via their servers Privacy: Data stored on company servers Verdict: Web-based so inherently synced

Bookly

Sync: No Privacy: Local only Verdict: Good privacy but no sync — dealbreaker for multi-device users

Leaflet

Sync: Yes, via iCloud Privacy: Data in your private iCloud account only Verdict: Full sync with privacy protection

The Future Expectation

Users increasingly expect:

• All apps sync by default
• Their data accessible everywhere
• No data loss during device transitions
• Privacy respected regardless

Single-device apps feel anachronistic. The friction of managing data across devices manually belongs to a previous era.

For something as important as reading history — potentially years of data — sync isn't optional. It's essential.

Choosing Based on Sync

If you use multiple Apple devices, prioritize apps that:

1. Sync via iCloud — Your data, your account, your control
2. Work offline — Sync catches up later
3. Sync quickly — Changes appear in seconds
4. Preserve everything — All data, all devices, all the time

Don't compromise on sync for any other feature. An app with great features but no sync is an app you'll eventually abandon when you switch devices or want your data elsewhere.

Your reading history is too valuable to trap on a single device.

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Seamless iCloud Sync with Leaflet

Leaflet syncs your entire library across all your Apple devices using your personal iCloud account.

How it works:

• Add a book on iPhone → appears on iPad instantly
• Track a reading session on iPad → shows on your Mac
• Update progress anywhere → synced everywhere
• All through your iCloud, not our servers

What syncs:

• Complete book library
• All ratings and reviews
• Reading progress
• Reading sessions and time
• Notes and quotes
• Goals and statistics
• Everything

Privacy preserved:

• Your data stays in your iCloud
• Encrypted with your keys
• We never see your reading history
• We can't access your data even if we wanted to

Works offline:

• Track reading without internet
• Add books offline
• Sync catches up when connected

No fragmented libraries. No lost history. No starting over when you get a new phone.

Download Leaflet — Sync across all your devices.