Syncthing: Syncing All the Things

Syncthing is one of the "fire and forget" kind of programs. It takes some time to setup when doing for first time, but then you pretty much forget its there, and when you need it, you realise it has been chugging along doing its job.

Two things I like about it in particular, are

1. It can and favors syncing over local network. This has a huge cost savings in developing world. Even when you do have massive bandwidth, local network sync still has more throughput and lower latency. My music is shared between devices and if I add a track, it takes less than a second to appear on my other devices.

2. You can set conditions, such that delets can be ignored. Eg. I have a WhatsApp message+media backup going back almost 7 years now, ~65GiB. But I don't need all that on my phone. So I just disable syncing delets on my storage. Now my phone can get away with ~3 GiB of whatsapp data (only because I don't delete very often) and I still have complete backup in case I need it.

3. Absolute rock solid stable. At $DAYJOB we use syncthing to sync multi dozen GiBs of new data every day, total file count in 10s of thousands in about ~300 directories. And in past 5 years we have had about 3 instances where we had something that needed attention, out of which 2 were not syncthing's fault.

I've been using Syncthing for years and have absolutely zero complaints against it. Everyone with 2 or more devices should give it a try, just to see there are better options out there.

I've been using Syncthing for years now, between ~10 Linux servers, Linux desktops, Linux and Windows laptops and Android smartphones, over LAN, wired and wireless Internet.

I'm synchronizing less than 100 MiB of data, but it's changing all the time. I've not yet had a single issue with it. I've a few conflicts every week when the same file is changed in different locations at the same time, but Syncthing keeps all versions of a file until I resolve the conflicts; I can't see how it could handle that better.

Long story short: I highly recommend this tool.

On of my favorite program, and it keeps getting better.

You can even set an encryption key per share, and if you want to use an untrusted device in your nodes, you can simply not provide it with the encryption key and it will simply synchronize the encrypted payload across nodes.

So if you have a shady/cheapo VPS, you can use its storage without worrying about the plaintext data being stored there.

Syncthing has re-framed how I think about the file systems of my computers. I used to occasionally plug in my phone to sync pictures and documents to my desktop. Now I don't even think about the distinction between them - the files simply exist on all of my computing devices, and any changes I make automatically propagate to the other devices.

I normally do all my work on my laptop, but I went ahead and set up sync between my work folders and my personal desktop. Syncing ~1tb of work data has been no problem.

I turn off my computers when I'm not home, and my phone runs syncthing-fork on a limited schedule, so I did at one point have some issues with stuff not syncing because devices weren't turned on. So I set up syncthing on a raspberry pi with a big external hard drive plugged in, and it sits next to the router just quietly synchronizing everything in the background.

It's all very set-it-and-forget-it. Just a great piece of software.

SyncThing and FreeFileSync make computing so much nicer for me, I would not ever want to go back.

After several attempts, I ended up dividing the SyncThing folders by device storage and level of trust. Simply put, there are things I don't want on my tablet because it has very little storage space, but I still want small things like my todo list and my keypass database there. Then there is stuff I don't mind having on my work laptop, that's mostly stuff like music or personal things that are not sensitive, like desktop wallpapers (so no private stuff I would minder others at work seeing, and no work stuff I would mind being stolen from my other devices). Then there are things I want on my laptops and desktops, but not on my phone, because they're either too big or only useful on a computer, like downloaded software. That's about it, and this way I only have to think about what to put in those folders, but I don't really add new synced folders a whole lot, and when I get a new device, it's self-evident what folders "should" be on it.

FreeFileSync is for stuff I sync manually, e.g. Firefox and Thunderbird profiles, htdocs folder and MySQL database. The only reason is that if I forget to stop Firefox, Thunderbird, or my webserver before starting it elsewhere -- which I should never do, but it can still happen -- and try to sync, I get a much nicer graphical interface to resolve conflicts en masse.

Syncthing can be a little confusing if you are coming from something like Dropbox or WebDAV. It’s not really quite like anything else I’ve used.

And with that having been said, it’s great. It’s maybe more powerful than you’d expect. My NAS for example has a one-way synced folder from a different box for backup, while having a default shared folder with all of my PCs. It’s also great because not all machines have to always be online; it can gracefully handle deferring stuff. For me, since my NAS is connected all the time, I can use it a bit like a central service, syncing between machines that have no overlap in uptime. Simultaneously, if the NAS needs to be down, it doesn’t interrupt syncing between other nodes. And unlike centralized solutions like Dropbox, I’m not limited by my internet connection, since it’s all local... unless I leave the house. In which case Syncthing appears to continue to stay connected, which is really handy.

SyncThing is an absolute treasure. I mean I have 20 years of rsync scripts, I've used Unison for real. But SyncThing is next level. The key part is once you have it set up it just runs and runs reliably without any attention. Also it works great on Windows too, including handling differences in filesystem semantics with Linux. Really well done.

I mostly use it to keep Windows' Document folders in sync across various machines (through a Linux server). Windows apps still put files in lots of random places but most of the important stuff is in Documents these days. I also use it to sync GPS traces from GPSLogger on an Android phone to my server. The Android app works great!

The setup of a new node is more complicated than it should be, that's the one product weakness.

In 2014 I tried to reduce my "cloud" usage and went from Dropbox → BitTorrent Sync (now Resilio Sync) → Syncthing. I have it running on all computers, tablets[0], and phones[0] I have/manage. In total, it keeps ~70K files and ~9TB in sync across devices running Android, macOS, Windows and Linux/Ubuntu/Raspberry Pi OS.

I don't remember when was the last time I had to use a flash drive or a cable to move files around.

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[0] Android. iOS is too restrictive to do this.

Syncthing has a good approach to telemetry. It optionally collects stats and makes them publicly available.

https://data.syncthing.net

Note well that in the default config, syncthing grants remote code execution on your machine to the syncthing developers in the form of Solarwinds-style no interaction autoupdate.

A compromise of the centralized release process could steal all of your (and everyone else's!) files by updating to a malicious version automatically with zero interaction.

Set the syncthing binary's file ownership as root and run it as a normal user so it can't get overwritten, and set STNOUPGRADE=1 in the environment to disable this dangerous default behavior.

Syncthing has worked flawlessly for me for years. Syncthing-fork on Android also works very well:

https://play.google.com/store/apps/details?id=com.github.cat...

Past threads:

Syncthing: Untrusted (Encrypted) Devices - https://news.ycombinator.com/item?id=27702785 - July 2021 (5 comments)

Open Source Continuous File Synchronization - https://news.ycombinator.com/item?id=27149002 - May 2021 (146 comments)

Syncthing Untrusted Device Encryption - https://news.ycombinator.com/item?id=26424096 - March 2021 (1 comment)

Syncthing is everything I used to love about computers - https://news.ycombinator.com/item?id=23537243 - June 2020 (159 comments)

Do not use Syncthing (2019) - https://news.ycombinator.com/item?id=23116462 - May 2020 (1 comment)

Emacs' Org-Mode and Syncthing = Perfect (2017) - https://news.ycombinator.com/item?id=23058358 - May 2020 (77 comments)

Syncthing: An open source Dropbox replacement - https://news.ycombinator.com/item?id=20466469 - July 2019 (41 comments)

Syncthing graduation day - https://news.ycombinator.com/item?id=18832517 - Jan 2019 (114 comments)

Syncthing Usage Data - https://news.ycombinator.com/item?id=13856552 - March 2017 (119 comments)

Syncthing - https://news.ycombinator.com/item?id=10331031 - Oct 2015 (1 comment)

Syncthing: Open Source Dropbox and BitTorrent Sync Replacement - https://news.ycombinator.com/item?id=7734114 - May 2014 (184 comments)

Recently, there had been an article in a prominent German IT magazin about using Synthing to create backups from any type of machine on a Raspberry Pi. So last week I tried it out and quickly run into a problem that could have been dangerous. What I tried out was to backup my Firefox and Thunderbird profils with synthing. I switched on simple file versioning to be on the save side even in case that something is accidentally deleted. The problem was that, probably due to interrupted synchronisation sessions, Synthing could not decide whether the file version on the orginal or on the backup machine is the most recent one. In this case it transfered an old file version with some additional intermediate filename extension from the backup to the original machine. So I ended up having doublicates of my email inbox and other folders in my Thunderbird profil that Thunderbird nevertheless recognized as valid inboxes, etc. The problem was easily solved by searching for the intermediate filename extension and deleting all those files manually. This experience suggests to me that it is perhaps not a good idea to use Synthing for anything else than the deliberate exchange of manually managed files in folders only and specifically dedicated to synchronisation.

One of the things I have found very useful is to configure Syncthing to have "sync only once" folders (it sends the file only one time).

In order to do that, I:

- Set a folders in a device to "send only". - Set a folder in a different device to "receive only". - Set the "Ignore delete" advanced option for the desired folders on both devices.

And that's it! I use it mainly to do some manual processing of the received photos and videos with Shotwell (copying and sorting my library into Year/Month/Day directories).

You may run into some issues where you may be promoted to "revert local additions" (I think on the receiver's end)... This mainly happens for two reasons:

- if you deleted a file on the receiver's "sync only once" folder - if you use a single folder where there may be other incoming files from other synced folders.

It is best to avoid the latter scenario; a quick fix for the first one is to make sure to delete the media first in the sender's device's folder and afterwards delete it on the receiver's device's folder.

After that, you can click "revert local additions", and the message should go away.

A long time ago, I used CrashPlan for backups. They had support for Linux, and I had a Linux server at the time that ran ownCloud and some other services that needed backups. I pointed CrashPlan at the appropriate directories and let it roll.

Fast forward several years, I needed to restore something (non-critical) and it was a giant pain in the ass. I was able to get it done, but it wasn't immediately clear that I would be able to. Something about CrashPlan not retaining deleted files and some of my paths changing or something.

Anyway, I was so frustrated by the whole experience that I dumped CrashPlan.

I run Syncthing to provide file sync services. A Raspberry Pi acts as the "central server" on my home network. Once a night, an EC2 instance launches, syncs the data up, and then performs an offline backup to S3. I get a report e-mailed to me every night so I can keep tabs on stuff.

I did have to spend time building it out, but it costs something like $5 per month and it's been bulletproof.

Lots of love for Syncthing over here. It's been a champ.

I love Syncthing. I've found some unconventional uses for it in syncing program settings. My fonts folder is now synced between my Mac, Windows and Linux computers and that works surprisingly well. My projects folder does a one-way archive (like rsync) for backup to my home NAS and an offsite VPS. I have a Streamdeck that I use between my Mac and Windows work machines, and I sync the settings on that so it operates the same way regardless of which machine I plug it into. I love it.

I sync my android phone to my laptop using syncthing. Works great, and the ignore patterns below prevent annoying access warnings.

Folder Type: Send Only

Ignore Patterns:

  Syncthing/**
  Pictures/.thumbnails/**
  Android/data
  Android/data/**
  Android/obb
  Android/obb/**

Has anyone here switched between (from/to) ownCloud/NextCloud and Syncthing? I'm currently using ownCloud on a BananaPro and I'm really not happy with the performance, but also with some bugs that appear to be a result of this low performance. I have considered Syncthing before but I wonder if anyone else has made the same transition. I'm mostly syncing Windows desktops.

I like Syncthing, but it is significantly held back by Google's restrictions on running background apps on Android. Every working app has to display a persistent notification, and if you run xmpp client, vpn and Syncthing, on a phone with a notch, you are effectively down to ONE notification icon - it could be two but if you have more than that, they all collapse into an ininformative dot.

Working without a vpn and xmpp is a no-go for me, so I have to sacrifice Syncthing, running it only from time to time.

For iPhone and iPad: MobiusSync (which is a compatible, but non-free implemenation). Works great, just as SyncThing does.

Syncthing is a great tool : I've been using it for years for backups, picture synchronization between phone and computer, and as a way to share a KeePass DB. In all those years, not a single issue arise : you connect a device, decide what to share or not, and then just forget about it

I use syncthing to keep keepass and my private keys in sync across my devices, it's great for that works perfect with easy setup and its cross platfrom.

I tried to use it to sync SASS and webpack between developers and it didn't work, it seems to have an issue with node_modules has too many files for it to deal with and it thinks the directory is hundreds of gb and just stalls with a million years eta.

The versioning is cool too but I found it a bit flakey.

If you need reliable versioning and syncing of lots of files use GIT, if you need easy cross platform syncing syncthing is the way to go.

Syncthing is pretty awesome. It's versatile, I use it to sync photos from my phone to more stable storage but also on webservers to keep files in sync across a couple boxes.

TL;DR: give syncthing a try. first time setup is odd, then bam, your files magically sync anywhere with internet.

I carried around my 1GB Data Traveler flash drive with great conviction. Then, a massive 4G SanDisk drive I would 'never fill up'.

Then, when my 16GB Nexus 4 filled up, one day while I was MTPing my old pictures to my computer, someone told me about Dropbox and how it would sync my pictures for me. After living out of Dropbox for all my non-cold-storage files...I hit the free limit. But I was a student and didn't have money to pay per month.

Skydrive gave me 25 GB. And 3 successive phones ate that like candy. So start paying up Mister. ugh.

But then, Syncthing came along here on HN. I installed it onto my phone and pc for camera download. then another, and another, and a separate folder for sharing files with a colleague, then my work SAN got laggy and lost files, so syncthing to keep my work files local and synced between work devices to the rescue.

And now, I don't pay for storage. or I do, but it just happens to come with word 365, but I don't bother using it.

And the flash drives? I'm up to a 256GB Sandisk Pro of some kind, but only for 'just in case' scenarios. Syncthing handles all of my LAN files access needs.

I used syncthing for about 5 years but eventually just fell back to mounting centralized storage and dealing with the cases it was slow to access sometimes. There were a few sync conflict issues I ran into over the years once I stopped using it for "core document sync" where it was just <1G and <10000 files (especially when one device was disconnected for a plane flight and came back online with a queue of changes) but the big thing was there were a couple of times I didn't continuously check things were syncing and it turns out I made 2 copies of files with different edits because they didn't see each other or the main node at home went away and I didn't catch it. You just don't run into these problems with a centralized host.

Also it really ate up CPU/memory when I had a lot of files going. It was among the worst "spin up the laptop fans at idle" offenders, even more so than equivalent options like onedrive.

That being said it was really great for a subset of my use case and the problems I had with it border more on problems with the model rather than problems with the tool.

I looked into syncthing and have set up a folder pair as well but does anyone run a separate additional server to do remote access of a specific file they might want to download? I am wondering if there's any clashes to let's say having something like nextcloud folders overlap with the folders used in syncthing?

I am looking for an alternative that helps bridge the gap that is Google File Stream where even in windows it mounts as a drive but streams everything in the background as needed. Plex seems like a clunky way to go about it but I am open to any suggestions. The file stream feature was mainly used to stream videos in an uncompressed way.

I mainly do local sync between android and windows and a rpi. I would love to have file streaming type support for the android and maybe an ios device.

Android has a way to do file streaming built into some of the cloud manager apps but a diy solution might not have remote access.

I am open to any suggestions, I understand that syncthing is about p2p syncing and the model is mainly for whole file copy.

Syncthing is great, I've used it for years to sync all my stuff and it has always been solid. I even use it on my kindle fire tablet (there's a Syncthing app in F-droid).

My only annoyance with Syncthing is when I reinstall an OS on one of my machines. Let's say I'm syncing files between my main workstation, two laptops, a phone, and a cloud backup. Now I want to reinstall the OS on one of the laptops. When I install syncthing on that machine, it gets a new ID. I can make it join the sync swarm but all the other members will think it's a new machine and won't trust it so I have to go to each of the other machines and manually remove the "old" laptop and bring in the "new" one.

I know there's Syncthing lite, but is there a way to "browse" your synced folders (without actually syncing) and then mark them for syncing to the phone? I'd love it if I could do that because my phone's storage is obviously limited.

Anyone using Syncthing to sync SSH config/keys and (eg) bash/shell profiles between machines?

I’ve gone through various attempts at keeping things in sync across a couple of Macs but always seem to hit issues.. (the issues not being specific to Syncthing)

I've been using Syncthing for the past few days and it has been working flawlessly. One thing I haven't tried is syncing between Windows and UNIXes (macOS/Linux) - does anyone have experience around this? How do permissions work?

I've used syncthing without problems for years, but then recently had an issue where it seemed to duplicate an entire folder of files and all their contents and whenever I would delete the duplicate it would bring it back.

I was really annoyed with it until I realized, it's actually OSX's fault, because I renamed a folder from uppercase to lowercase, and there's no good way for syncthing to handle that when you have case sensitive servers syncing with insensitive ones. (Linux and OSX in my case.)

Moral of the story is, don't rename a file only changing it's case-- add a dumb character or something so it can sync to more civilized servers properly.

Absolutely top! I always recommend syncthing. I use it to sync and backup data in different situations which are all similar to what others reported here.

One thing I'd like to add is, that syncthing is also configurable in detail. I use it to sync data between a workstation behind restricted network and my laptops (most of $HOME). For this I use ssh-tunnels between the hosts. So syncthing's public discovery would not be necessary. I can directly set the tcp endpoints for syncthing so it find its communictation partners. Nice!

Anyone here who decided to try to sync files at TB scale?

And what about file holes? AFAIK syncthing filles them with zeros. Is this still the case?

How's the sharing situation nowadays? Tried Syncthing a few years back and while excellent and encountering zero problems, the UX for setting a share with someone else was a bit of a hassle compared to Resilio (which has been rock solid for the last decade for me as well). Sharing a single string and be good to go is UX you can't beat. Do you still have to go through the accept-peer-rigmarole with Syncthing, or have they added 'light weight' shares, for, you know, sharing?

shoutout to DecSync (https://github.com/39aldo39/DecSync) to use Syncthing with your CalDAV/CardDAV contacts/calendars/tasks and sync local RSS feeds across devices. I don't really use nextcloud anymore for stuff that is only for myself and does not need to be shared

For anyone getting into ObsidianMD, Syncthing works great to sync that. I use it to sync the vault folder between my phone, Chromebook and central NAS. Works great. I do ignore the Obsidian .workspace file to avoid extra battery usage.

It's also fantastic for backups from various VMs amd backing up photos from phones to my NAS, etc.

Over a year of use here, with about 75GB of my most critical document data across two Mac laptops and an old FreeBSD server. No hiccups. I use Documents.app on my iOS devices to access any of those computers via LAN versions or port-forwarded, out-of-the-house versions, and everything is great. Highly recommend.

The only thing I'm not quite comfortable with is that Syncthing takes significantly more hassle than Resilio Sync to set up. For every folder you need to manually approve every other device on every device, leading to O(kn^2) approvals where k is number of folders and n is number of devices.

Deployed Syncthing for the first time recently with Obsidian notes, setup was seamless on both Android mobile and Linux desktop (systemd), works flawlessly so far. Enormous upgrade over (lazily) using Google Keep for synced notes.

I've been thinking of buying a home NAS and running Syncthing as a replacement for Dropbox/Google Drive. Does anyone have any recommendations? Synology comes up a lot, I might also just use a Raspberry Pi.

The one thing I miss would be a somewhat more user friendly way to have file versioning along with a UI (doesn't have to be terribly user-friendly, my baseline is dropbox's interface)

Yep, I know that if I chuck stuff into my synced folders it goes around my machines, onto my NAS, and then onto Backblaze.

Check it out every now and then to make sure, but it just kinda works

I like syncthing, but when I was trying it on just 3 laptops on the same wifi network, the speed seemed much slower than what I expected the maximum to be.

(Anecdata I know).

Does it support syncing local folders? For example a game put saves in Documents folder and I would to sync it to my Dropbox folder, is such thing possible?

I wonder if it can sync files from a machine in China to a machine in US which doesn’t have great firewall implemented. Anyone tried this?

I was disappointed with the slow sync speed, as in sync 'realization' compared to say Dropbox, but it's great otherwise

It's great. Big thanks to those that run relays.

It's not a backup solution though... you really want to use actual backup software.

Any third party app that can sync a Synchting folder on iOS (with other Synchting instances on desktop and android)?

Had to stop using it because the devs couldn't fix the SD card issue on Android.

They support arbitrary locations on external SD cards on Android yet?