Cloud to cloud file transfer: how to move files without downloading them

    Cameron James·
    · 6 min read
    Document sharingFile sharingFile hosting

    Cloud to cloud file transfer means moving files from one cloud service to another (Google Drive to Dropbox, OneDrive to S3) without pulling them down to your laptop first. The honest answer to "how" depends on one question: does the copy happen on the provider's servers, or through your machine?

    Most of the time it's through your machine. That's why moving 80GB between two accounts takes a weekend and dies when your Wi-Fi blinks.

    Before you pick a tool, though, check whether you need to transfer anything at all. I'll come back to that.

    The three ways a cloud to cloud transfer actually works

    Every method fits one of these, and knowing which one you're using explains most of the speed and failure problems.

    Download and re-upload through your device

    The manual version. Download from service A, upload to service B. Your connection carries every byte twice, and your upload speed (usually the slow one) sets the pace.

    It's fine for a folder of PDFs. For anything big it's miserable, and a dropped connection often means starting again.

    Transfer tools that run the copy for you

    Services built for this connect to both accounts and run the transfer from their own infrastructure, so your laptop can be shut. You authorise each account, pick the source and destination, and it works through the queue.

    Fewer failures, no babysitting. The trade-off is that you've just given a third party access to both accounts. Read what permissions you're granting before you click through, and revoke access when the job is done.

    Server-side copy

    The cleanest option, and the narrowest. The provider copies the data internally and nothing travels through you. The command-line tool rclone documents this well: when it applies, it "won't download all the files and re-upload them; it will instruct the server to copy them in place".

    The catch is in the same docs. Server-side copies are only attempted when the remote names are the same, for example two buckets on the same storage service, and remotes that can't do it will download and re-upload instead. So it works within a provider, and rarely between two different ones.

    Why cloud to cloud transfers fail

    Moving files between accounts is the kind of job that looks like ten minutes and eats an afternoon, and the failures are boring and repetitive.

    • Native formats don't survive. Google Docs, Sheets and Slides aren't ordinary files. They get converted on export, and formatting can shift on the way.
    • Permissions don't move. Files arrive, sharing settings don't. Everyone who had access has to be re-invited.
    • Size limits differ. Google says most files can be up to 5 TB, but converted documents and spreadsheets have much lower caps. Other services have their own ceilings, and a limit you never hit on one side can stop the job on the other.
    • Rate limits and timeouts. Big batches of small files are often slower than a few large ones, because each file carries overhead.

    My rule: transfer a small test folder first, open the files at the other end, and only then run the big job.

    Do you need to transfer the file, or just share it?

    This is the part most guides skip. A lot of people searching for cloud to cloud file transfer aren't migrating anything. They're trying to get a file from their cloud into someone else's hands, and they've assumed that means copying it into the other person's cloud.

    It doesn't. A link does the same job with nothing to copy, nothing to keep in sync and no second version of the file to go stale. If the other person only needs to read it, send a link.

    That's the case for documents especially. If the thing you're moving is a proposal, a report or a deck, the recipient wants to read it, not store it. For a PDF or an image, that's what LiveDocument is for: you upload the file once, attach a video walkthrough, and send one link to the PDF. You can expire or revoke the link later. It isn't storage and it isn't a migration tool, so it won't move your 80GB archive. If you want to see the sharing options side by side, my file sharing software overview covers where it fits, and there's a fair LiveDocument vs Google Drive comparison too.

    For large videos and other big files that need to arrive intact, I've written up the options in how to share large files on a Mac and the best way to send multiple files via email.

    A quick way to choose

    Match the job to the method:

    • A handful of files, one-off: download and re-upload. Don't over-engineer it.
    • Whole folders or accounts, two different providers: a transfer tool, with a test run first and access revoked afterwards.
    • Same provider, different buckets or accounts: server-side copy where the service supports it.
    • Someone just needs to see the file: skip the transfer and send a link.

    The last one is the most common and the least searched, which is a bit mad.

    FAQ

    Can I transfer files between Google Drive and Dropbox without downloading them?

    Yes, using a third-party transfer service that connects to both accounts and runs the copy on its own servers. Neither provider copies directly into the other, so some tool is always in the middle.

    Is cloud to cloud transfer secure?

    It depends on the tool. You're granting access to both accounts, so check the permissions requested, prefer services that explain how data is handled in transit, and revoke the connection once the job is finished.

    Does cloud to cloud file transfer keep sharing permissions?

    Usually not. Files move, but who could see them generally doesn't, so plan to re-share after a migration.

    What's the easiest way to send a cloud file to someone else?

    Share a link rather than copying the file. For PDFs and images you want explained, a PDF with a video walkthrough goes out as one link.

    If you're sending documents rather than moving archives and you're tired of not knowing whether anyone got past page one, that's the problem I built LiveDocument for. It's at livedocument.com.

    About the Author

    Cameron James

    Cameron is the founder of LiveDocument. He writes about sharing documents, PDFs, decks and contracts, and why pairing a video walkthrough with a document beats sending it cold.