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What Are the Best File Sync Tools?
The best file sync tools for most people are OneDrive for Windows and Office users, Google Drive for Gmail and Android users, Dropbox for fast, reliable sync across mixed systems, and iCloud Drive for Apple households. For privacy, choose an end-to-end encrypted service or a peer-to-peer tool like Syncthing.
| Tool | Free storage | Version history (consumer) | End-to-end encryption | Linux app | Best for |
|---|---|---|---|---|---|
| OneDrive | 5 GB | 30 days | No (Personal Vault adds extra sign-in) | No official app | Windows and Microsoft 365 users |
| Google Drive | 15 GB, shared with Gmail and Photos | 30 days or 100 versions | No | No official app | Android and Google Workspace users |
| Dropbox | 2 GB, up to 3 devices | 30 days on Basic and Plus | No, not by default | Yes | Mixed Windows, Mac and Linux setups |
| iCloud Drive | 5 GB | Recently Deleted for 30 days | Yes, with Advanced Data Protection | No | iPhone, iPad and Mac owners |
| pCloud | Up to 10 GB | Up to 30 days (longer with an add-on) | Paid add-on | Yes | Lifetime-plan buyers who want Linux |
| Syncthing | No cloud storage (uses your devices) | Optional file versioning | Encrypted device-to-device | Yes | Privacy, no provider at all |
| Resilio Sync | No cloud storage (peer-to-peer) | Archive folder | Encrypted device-to-device | Yes | Large files and NAS users |
Facts were checked against each provider’s published documentation in October 2026. Free storage and plans change, so confirm on the provider’s site before you buy.
How We Compared These File Sync Tools
We compared every tool on the same six points. These are the points that decide whether sync works day to day, not just on a features page.
- Sync reliability: how the app handles large folders, many small files and interrupted connections.
- Conflict handling: whether the app keeps both versions when two devices edit one file.
- Version history: how long you can roll back a file on a consumer plan.
- Encryption model: who holds the keys.
- Platforms: Windows, Mac, Linux, iOS, Android and NAS support.
- Limits: file size, path length and blocked characters.
The data comes from each provider’s documentation, checked in October 2026, and from ten years of setting up and fixing these apps. We did not accept payment for placement.
Short Verdicts on Each Tool
OneDrive
OneDrive is built into Windows, so it is the easiest choice on a Windows PC. Files On-Demand saves disk space, and Office files support live co-authoring.
Microsoft lists a 250 GB file size limit and a 400-character path limit. There is no official Linux client. See our OneDrive not syncing fixes if it misbehaves.
Google Drive
Google Drive gives the most free space, 15 GB, but Gmail and Google Photos share it. Drive for desktop offers stream or mirror modes on Windows and Mac. Our Google Drive sync guide covers setup.
Dropbox
Dropbox has a strong reputation for fast block-level sync and supports Linux. The free Basic plan is small, at 2 GB and three devices. It handles conflicts by saving a clearly named conflicted copy. Read Dropbox sync explained for details.
iCloud Drive
iCloud Drive is seamless on Apple devices and works on Windows through the iCloud for Windows app. It has no Android app. Advanced Data Protection adds end-to-end encryption for Drive, Photos and backups.
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pCloud
pCloud supports Windows, Mac and Linux and offers lifetime plans. File history and Rewind cover up to 30 days, with an add-on for longer. End-to-end encryption needs the paid pCloud Encryption add-on.
Syncthing
Syncthing is free, open source and peer-to-peer. Files travel directly between your devices, encrypted, with no provider storing them. It needs at least two devices online at the same time. Set it up with our Syncthing cloud guide.
Resilio Sync
Resilio Sync is also peer-to-peer and handles very large files well. Resilio now includes features that once required a paid Pro plan in its free download. It runs on many NAS devices. See our Resilio Sync review.
Which Sync Tool Suits You?
- You use Windows and Office: OneDrive.
- You live in Gmail and Android: Google Drive.
- Your household mixes Windows, Mac and Linux: Dropbox or pCloud.
- You only use Apple devices: iCloud Drive with Advanced Data Protection.
- You want no third party at all: Syncthing, or Resilio Sync on a NAS.
- You want free sync only: see our list of free cloud sync options.
Whichever tool you pick, remember that sync is not a backup. Our guide to file sync explains why, and how to add a real backup.
Frequently Asked Questions
What is the most reliable file sync tool?
Reliability depends more on setup than brand. Dropbox has a long record of fast, stable sync across Windows, Mac and Linux. OneDrive is most reliable on Windows because it is built in. Whatever you choose, avoid blocked characters, long paths and syncing the same folder with two apps at once.
Can I use two sync tools at the same time?
Yes, as long as each tool syncs a different folder. Problems start when two apps watch the same folder, because each sees the other’s changes as new edits and can create loops or duplicates. Keep separate folders, such as one for OneDrive and one for Google Drive.
Which file sync tool is best for privacy?
For privacy, choose a tool where only your devices hold the keys. Peer-to-peer tools like Syncthing store nothing on a provider’s servers. End-to-end encrypted services like Proton Drive, Tresorit or iCloud with Advanced Data Protection also work. Mainstream services like Google Drive and Dropbox hold the keys by default.
Is there a free file sync tool without storage limits?
Syncthing is free and has no storage limit because it uses your own devices instead of cloud storage. Your limit is the disk space on those devices. Resilio Sync also offers a free download. Cloud services always cap free storage, from 2 GB on Dropbox Basic to 15 GB on Google.
Do file sync tools work on a NAS?
Many do. Synology and QNAP offer their own sync apps, and Resilio Sync and Syncthing run on many NAS models. Mainstream services like OneDrive do not install on a NAS directly, but NAS apps such as Synology Cloud Sync can connect to them. See our cloud NAS guide for options.
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Sources
- Restrictions and limitations in OneDrive and SharePoint (Microsoft Support)
- Files you can store in Google Drive (Google Drive Help)
- Check activity and file versions (Google Drive Help)
- What is the Dropbox file size limit? (Dropbox Help)
- iCloud data security overview (Apple Support)
- pCloud Backup features (pCloud)
- Resilio Sync (Resilio)
- Syncthing documentation
