What Is Cloud to Cloud Sync?
Cloud to cloud sync copies or mirrors files from one cloud provider to another, such as Dropbox to OneDrive or Google Drive to pCloud, without storing them on your own disk. A tool links both accounts and moves files between them. Use a one-way copy for backups and migrations, and two-way sync only when people work in both clouds.
| Mode | What happens | Deletes files? | Use for |
|---|---|---|---|
| Copy (one-way) | New and changed files go from source to target | Never | Backups and migrations |
| Sync or mirror (one-way) | Target is made to match the source | Yes, on the target | Exact replicas |
| Two-way sync | Changes flow both directions | Yes, on both sides | Teams split across two clouds |
| Move | Files copied, then deleted from source | Yes, on the source | Final migrations |
Ways to Sync Cloud to Cloud
rclone (free, any provider)
rclone is a free, open-source command-line tool that supports dozens of providers, including OneDrive, Google Drive, Dropbox, Box, pCloud, Backblaze B2 and Amazon S3. It runs on Windows, Mac and Linux and can be scheduled.
Web-based transfer services
Several companies offer cloud-to-cloud transfer through a website. They run without your computer, but your files pass through their systems. Check where they are based and what they store.
Two desktop apps on one computer
You can install both providers’ apps and use a folder sync tool between them. This needs local disk space, but it is easy to understand. Our hub on how to sync OneDrive to Google Drive walks through it.
NAS cloud sync apps
Many NAS devices include apps that connect to several clouds at once, such as Synology Cloud Sync. The NAS acts as a hub. See NAS sync.
Step-by-Step: Cloud to Cloud Sync With rclone
- Install rclone from rclone.org.
- Add the first cloud. Run
rclone config, choose n for a new remote, name it (for examplesrc) and pick the provider type. Sign in when the browser opens. - Add the second cloud the same way, named
dst. - List files to test the connection:
rclone lsd src:andrclone lsd dst:. - Preview the copy:
rclone copy src:Folder dst:Folder --dry-run. - Run the copy:
rclone copy src:Folder dst:Folder --progress. - Check the result:
rclone check src:Folder dst:Folder. - Schedule it with Task Scheduler on Windows or cron on Mac and Linux.
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Requirements and Limits to Plan For
- Storage at the target. Check free space before you start.
- Provider rate limits. Google limits uploads to 750 GB per user per day. Other providers throttle heavy API use.
- File rules. A file allowed in one cloud may break another’s limits, such as OneDrive’s 250 GB file cap or 400-character paths. See cloud storage limitations.
- Native document formats. Google Docs, Sheets and Slides export to Office formats when copied out.
Common Errors and Fixes
| Error | Cause | Fix |
|---|---|---|
| Rate limit or 429 errors | API throttling | Lower speed with --tpslimit and retry |
| Files skipped | Name or size breaks target rules | Rename, shorten or split the files |
| Duplicates on target | Job run into two different folders | Use one fixed target path |
| Deleted files vanished from both | Two-way or sync mode used | Restore from each cloud’s recycle bin |
| Token expired | Password changed or access revoked | Run rclone config reconnect |
How to Verify Cloud to Cloud Sync
- Run
rclone checkor compare folder sizes on both websites. - Open a few files of each type on the target.
- Add a test file to the source, run the job again, and confirm only that file copies.
Common Mistakes
- Using sync when you meant copy. Sync deletes on the target.
- Skipping the dry run. Always preview first.
- Treating a second cloud as a full backup without versions. Choose a target with version history, or a backup service. Read back up to the cloud.
Specific pairs: Dropbox Google Drive sync, OneDrive to Google Drive and iCloud and OneDrive.
Frequently Asked Questions
Is cloud to cloud sync faster than downloading and uploading?
Usually, yes, and it saves your disk space. Tools like rclone stream data from one provider to the other without storing a full local copy. Web services move data between data centres, which can be faster than a home connection. Provider rate limits still apply, so very large transfers can take a day or more.
Which tools support cloud to cloud sync?
rclone is the most flexible free option and supports dozens of providers. Several web-based transfer services also exist, usually with free tiers and paid plans. NAS apps like Synology Cloud Sync can connect multiple clouds. Your choice depends on whether you prefer a free tool you run or a hosted service.
Can cloud to cloud sync work as a backup?
A one-way copy to a second provider gives you an independent copy, which helps if one account fails. It is not a full backup unless the target keeps older versions. Use copy mode, never two-way sync, and choose a target with version history or object lock for real protection.
Is cloud to cloud sync secure?
With rclone, data moves directly between you and the providers using their official connections, and you can encrypt files with rclone’s crypt feature. Web services handle your files and access tokens on their servers, so review their security and privacy policies. Revoke access from your account settings when you stop using a service.
What happens to file versions when I sync between clouds?
Only the current version of each file is copied. Version history stays with the original provider and does not move to the target. If older versions matter, keep the source account for a while or restore the versions you need before moving.
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