BitTorrent Sync: synchronize folders on multiple PCs securely without uploading to a cloud server


While Dropbox and other cloud services have made syncing folders on multiple devices ubiquitous, there is a way to do the same thing without uploading your files to the cloud, from one device to another straight while cutting out the middleman.

This, at least, is what free ‘BitTorrent Sync’ does, directly, automatically, and securely, using torrent technology.

There is a simple concept here: by utilizing torrent technology, you can sync folders directly from one machine to another, without uploading them to a cloud server or anywhere else. There are several advantages to this and some disadvantages, which we discuss below:

BiTorrent Sync Screenshot3 - system tray notification

PROS: the advantages of direct syncing:

  1. Security: actual file transfers are encrypted, and nobody has a copy of your files floating in a server somewhere. You don’t have to worry about the honesty or credibility of an intermediary, and you do not have to worry about their violating their terms, in case that ‘Muse’ concert you filmed on your iPhone is considered copyrighted material or whatever.
  2. No Size Limits: beyond the hard drive space on your PC. Otherwise, the syncing will simply continue until it is complete (making this one of the best ways to share extremely large files, really).
  3. You can sync any folder: directly and without copying into a special folder or even using symbolic links. It would be nice if they added a Windows context menu entry

BiTorrent Sync Screenshot2

CONS: the disadvantages

  1. Your files will not be backed up unless both PC’s were simultaneously active: in other words, there is a need to verify that you don’t have to deal with when using a typical cloud service.
  2. You cannot access files on the go: since your files are not on a server, you cannot decide to download in the spur of the moment by accessing a webapp on any random computer as you would with Dropbox.
  3. No versioning: while Dropbox and others will maintain several past versions of a file (which I can attest can at times be extremely convenient), the current version of BitTorrent Sync that I tested do not UPDATE: versioning is supported for up to 30 days.
  4. No mobile support as of yet: this app is in alpha, and currently there are no mobile apps on offer. This is probably temporary: we envision mobile apps popping up in the not so distant future, although we did not read this on their site.

How to use:

Run the program and select the ‘Shared Folders’ tab, which shows synced folders. Add a folder via the buttons toward the bottom and you will be presented with a ‘shared secret’ code (see below). Copy this code and then use it to sync to a folder on another device, and they will be linked.

BiTorrent Sync Screenshot1 - Add a folder

Note that there are four kinds of possible access; full access, read only, and 24-hour duration access (also full or read only). You can get these by right clicking properties on a shared folder and sharing the appropriate ‘secret’ code.

The verdict:

This simple alternative to Dropbox will not have me uninstall Dropbox and abandon the cloud, but it has huge appeal, especially for very large files or archives that I do not want to upload to the cloud but that I would love to sync on multiple PCs. I already have both installed on my computer and am using both.

For sharing large files, BitTorrent Sync is perfect, doing the job efficiently without consuming all of your cloud storage. It is also perfect if you want to use that old beat up laptop or desktop you have for backup purposes, and doing it automatically without any manual intervention.

It is also perfect for the security minded, who do not want copies of their files living somewhere on a cloud server.

There’s a lot of room for improvement, though, including mobile apps, desktop apps for Mac and Linux, and better Windows integration (e.g. adding folders via the context menu).

Let me know if you can think of other uses where BitTorrent Sync can take over from Dropbox.

Get Bittorent Sync here.

  • kalm-man

    BitTorrent Sync isnt a Dropbox alternative, is a new category if you wish… or an old one if you take in consideration the file upload sites (not talking about torrent sites!)

    If you ever tried to transfer that 1.5G of photos or video you shut in a day you know ho stupidly hard it is 😛 over IM even Gtalk you dont get more than 300kb/s of upload speed, shared dropbox folder/link has the same speed and max out your space, upload to a dedicated site without payed account you get the same or even smaller upload speed and a lot of limitations like max file size, aviability of the file for limited time etc.
    If your connection fall for 1 second you are good as new to start uploading again.

    The torrent protocol can maximize your upload speed so instead of 300kb/s I can use all my real 10+MB/s, and Im the only one in control of it.

    This can lead also to wider “legalization” of bittorrent protocol, so ISP’s wont throttle any more and even Dropbox can learn something here because the torrent protocol would give them too some good points 🙂

    • Yes, I agree. As I was reading Samer’s comparison of the product to DropBox, I thought to myself that that’s not what it is, really.

      It seems to me, from its both capabilities and limitations, coupled with having “bit torrent” in its name, that it’s a response to the whole six strikes thing…

      SEE: (Slash Gear article)
      SEE: (Google search: “six strikes”)

      …so that any two (or potentially more) people may still exchange files, but without there being any public tracking, as with actual Bit Torrent clients. If that’s all it’s used for, then some of Samer’s “cons” become kinda’ moot.

      Yes, of course, the parties thinking that they could use a tool like this instead of regular Bit Torrent would have to first connect in other ways, but that’s certainly a no brainer. I’m not saying that this tool is an adequate hedge against six strikes; turns out, it seems difficult, indeed, to even trigger it, we’re learning. And, anyway, UseNet is probably the solution to six strikes… just my opinion, mind you.

      Thanks, Samer, though, for the article. Excellent, as usual!

      Gregg L. DesElms
      Napa, California USA
      gregg at greggdeselms dot com

  • Mike

    LogMeIn’s Cubby does this as well. It has a sync from multiple computers without necessarily going to the cloud ( it’s an option ).

    That being said, I believe to use that feature now, you have to pay for their premium service. But it works fantastically well for larger files, and it’s quite easy to setup….

    Just an option even though that portion isn’t freeware.

  • Excellent post. Been searching for this actually & found it what i need.Only mobile support & not backing up downloading files seems less advantage to me. Otherwise useful in all ways. Thanks.

  • WJ

    This is going to be REALLY useful to me! Excellent….can’t wait to put it to the test

  • Brousse.ouillisse

    This tool is excellent as it allows me to synchronize my 500 GB of documents, photos, videos, musics between my PC (desktop+laptop). To be honest, I first used alwayssync freeware to synchronize my documents with an external hard drive THEN I set up BTSync to initialize synchronization.
    And this is just excellent !
    And I guess there should a way to use a cloud service as a partial online buffer, so I can have some files synchronized in PC1Cloud servicePC2.
    Of course computers have to be on simultaneously, but letting them working one hour every week to ensure the synchronisation is OK for me.