Free tools Windows power users keep installed
One-click scans. No signup required.
iTechGuides is reader-supported. When you buy through links on our site, we may earn an affiliate commission. As an Amazon Associate I earn from qualifying purchases. Learn more
Syncthing lets you synchronize selected folders directly between devices you control, without uploading the files to a conventional cloud-storage account. Install it on every device, exchange each device’s ID, share a specific folder, and verify a test file. The files move only while participating devices are online together; connection discovery and relay services can still see network metadata, so private syncing is not the same as anonymity.
What Syncthing does—and what it does not do
The Syncthing project describes its software as “an application that lets you synchronize your files across multiple devices.” In practical terms, it watches folders you choose and propagates additions, edits, moves, and deletions among the devices authorized for that folder. There is no required central cloud account holding a copy of the synchronized data.
Syncthing is a synchronization system, not a complete backup service, anonymous networking tool, or remote-administration platform. A deletion can synchronize just as an edit can. A lost device, corrupted file, ransomware event, or mistaken local change can therefore affect every online peer unless you have versioning and a separate backup.
The basic operating model
- Each installation creates cryptographic keys and a device identity.
- You authorize peers by adding their device IDs on both ends.
- You choose individual folders to share; nothing outside those folders is synchronized.
- Peers exchange changes when they can connect and are running.
- Transfers between devices are protected with TLS, while discovery and relay infrastructure can observe limited connection metadata.
Prepare before installing
Decide which devices should participate and which exact folder belongs in the sync set. Start with a small, non-critical folder rather than your entire home directory. Syncthing must be installed and running on each participating device, and each device needs a writable local path for its copy.
#1 Best Overall
- MADE FOR THE MAKERS: Create; Explore; Store; The T7 Portable SSD delivers fast speeds and durable features to back up any endeavor; Build your video editing empire, file your photographs or back up your blogs all in an instant
- SHARE IDEAS IN A FLASH: Don’t waste a second waiting and spend more time doing; The T7 is embedded with PCIe NVMe technology that brings fast read and write speeds up to 1,050/1,000 MB/s¹, making it almost twice as fast as the T5
- ALWAYS MAKE THE SAVE: Compact design with massive capacity; With capacities up to 4TB, save exactly what you need to your drive – from large working files to game data and everything in between
- ADAPTS TO EVERY NEED: Whether using a PC or mobile phone, count on the T7 for extensive compatibility²; It’s a true team player when it comes to heavy-duty application usage or file-saving
- HI RESOLUTION VIDEO RECORDING: Record Ultra High Resolution (4K 60fs) videos directly onto the T7 Portable SSD with your favorite camera or mobile devices; Supports iPhone 15 Pro Res 4K at 60fps video and more³
Checklist
- Two or more devices you control, with enough free disk space for a full copy of the selected folder.
- Operating-system accounts that can read and write the chosen paths.
- Permission to allow Syncthing’s sync traffic through local firewalls.
- A plan for what happens when a device is offline. Changes wait for a later connection; they are not uploaded to a cloud queue.
- A separate backup for files that must survive device loss, destructive edits, or synchronized deletion.
Syncthing’s packages and platform wrappers vary. Use the project’s current download or documented package source for your operating system instead of assuming every platform has the same installer or service behavior.
Install and open Syncthing on every device
- Install the current Syncthing build or distribution package on the first device.
- Start Syncthing. On first launch it creates its configuration, encryption keys, and web administration interface.
- Open the local administration GUI at
http://localhost:8384/. Keep this interface bound to the local host unless you have a specific, secured reason to administer it remotely. - Repeat the installation and first launch on the second device and any additional peers.
The first-run setup may create a default folder in the user’s Sync directory. You can use that folder for a quick test or replace it with a path you deliberately selected. Do not assume that a package’s default service starts at boot; check the operating-system integration for the build you installed.
Pair your own devices with mutual device IDs
Syncthing identifies a device with a public-key-derived Device ID. The ID is not a password and does not need to remain secret, but anyone who learns it may be able to use discovery information to associate it with an address. Device names shown in the GUI are only labels.
- On device A, open the GUI and choose Actions followed by Show ID.
- Copy the complete Device ID or display its QR code if the other device supports scanning.
- On device B, choose Add Remote Device, enter device A’s ID, and give it a recognizable name such as “Home laptop.”
- Perform the same operation in the opposite direction: show device B’s ID and add it on device A.
- Save the remote-device settings on both machines.
Pairing is mutual configuration. Adding only one ID does not complete the relationship; both devices must authorize one another. When a remote-device request appears, compare the displayed ID with the value you intended to add before accepting it.
Share one folder and verify the path
Folder sharing is separate from device pairing. A peer can be trusted as a device and still receive no files until you share a folder with it.
- On the device containing the source files, select Add Folder.
- Enter a clear folder label and a unique folder ID. The label is for people; the ID is how Syncthing matches the share.
- Set the local path to the exact directory you intend to synchronize. Check spelling, drive letters, mount points, and case-sensitive paths.
- In the folder’s Sharing section, select the remote device you paired.
- Save the folder configuration.
- On the other device, accept the folder-sharing request, choose the local destination path, and save it. The destination does not have to use the same absolute path or folder name.
- Wait until both GUIs show the folder as connected and in sync.
- Create a harmless text file, such as
syncthing-test.txt, in the shared folder. Confirm that it arrives on the peer, then edit or remove the test file and confirm that the expected change propagates.
Do not point a new share at a directory that already contains an unrelated set of files without checking the merge behavior. Syncthing compares file states; it is not a one-way “copy this folder over the top” command. A small test first confirms that the folder ID, peer selection, permissions, and local paths all match.
Rank #2
- Get NVMe solid state performance with up to 1050MB/s read and 1000MB/s write speeds in a portable, high-capacity drive(1) (Based on internal testing; performance may be lower depending on host device & other factors. 1MB=1,000,000 bytes.)
- Up to 3-meter drop protection and IP65 water and dust resistance mean this tough drive can take a beating(3) (Previously rated for 2-meter drop protection and IP55 rating. Now qualified for the higher, stated specs.)
- Use the handy carabiner loop to secure it to your belt loop or backpack for extra peace of mind.
- Help keep private content private with the included password protection featuring 256‐bit AES hardware encryption.(3)
- Easily manage files and automatically free up space with the SanDisk Memory Zone app.(5). Non-Operating Temperature -20°C to 85°C
Make devices connect on the same network or across the internet
What happens on a local network
Local discovery can find peers automatically when they are on the same network. Syncthing announces a device ID and listening port on the local network using IPv4 broadcast or IPv6 multicast. The project documentation describes local-discovery packets being sent approximately every 30 seconds. If local discovery is disabled, devices with changing local addresses may need another way to find one another.
Windows Errors? Fix Them Before They Spread
Repair common Windows errors and clear accumulated junk for a smoother, more stable PC - no reinstall needed.Free scan · no reinstallCrashes, No Sound, or Screen Glitches?
Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteWhat happens across separate networks
When devices are on different networks, Syncthing may use global discovery to learn addresses, establish a direct connection, or fall back to a relay. A direct connection normally provides the best transfer performance. A relay can still make synchronization possible when routers or firewalls prevent direct communication, but throughput is usually lower.
Default ports and firewall rules
Allow the following traffic for the default configuration. If you changed Syncthing’s sync port, use the port shown in the GUI instead.
| Purpose | Protocol and port | What to allow |
|---|---|---|
| TCP sync protocol | TCP 22000 | Incoming and outgoing traffic between participating devices, where your firewall policy requires explicit rules. |
| QUIC sync protocol | UDP 22000 | Incoming and outgoing traffic for QUIC connections. |
| Local discovery | UDP 21027 | IPv4 broadcast and IPv6 multicast discovery on the local network. |
Check the remote device’s status and the operating-system firewall before changing router settings or exposing the administration GUI. Opening a sync port may be necessary for a direct inbound connection, but opening the GUI to the internet is a different and much riskier change.
Compare the available connection paths
| Path | Direct connection? | Setup effort | Performance | Metadata exposure |
|---|---|---|---|---|
| Local discovery | Usually, when both devices share a LAN. | Low; allow local discovery traffic. | Usually high on a local network. | Devices on that local network can observe discovery announcements containing the device ID and listening port. |
| Global discovery plus direct connection | Yes, if addressing and firewalls permit it. | Moderate; verify firewall and router behavior. | Usually better than a relay. | The discovery service can receive device IDs, listening ports, and announcements that may map an ID to an external IP address. |
| Relay | No; traffic traverses a relay. | Low when direct connectivity fails. | Lower and dependent on relay capacity. | The relay can learn device IDs, IP addresses, and traffic volume, but the file data remains end-to-end encrypted. |
Global discovery announcements are documented as occurring every 30 minutes, while local discovery operates about every 30 seconds. These are implementation intervals, not measurements of privacy or reliability.
Keep the administration GUI local
The web GUI listens on the local host by default. That is a useful security boundary: someone who can reach the GUI may be able to change folder and peer settings. Leave it at the local address for ordinary setups.
Rank #3
- Capacity Display Variance: 250GB external ssd often appears as around 232GB on Windows. MacOS can show full 250 GB capacity. This is binary calculation difference and doesn’t affect SSD hard drive actual physical storage
- 1050 MB/s Speed: Instantly access to your files with blazing-fast 10Gbps external SSD read up to 1050MB/s and write up to 1000MB/s. LED Light indicates USB SSD instant activity
- Data Security: Solid state drives S.M.A.R.T. health diagnostics and adaptive TRIM optimizing data block management ensures consistent write speeds and extends the longevity of the portable SSD
- USB-C & USB-A Cable: Both cables featuring rapid USB 3.2 Gen2, this USB SSD effortlessly bridges devices, enabling seamless cross-platform file transfers and backup between computers, smartphones, tablets and iPhone
- Always Fast: No slowdowns for large file transfers. With SLC caching (25% of current available capacity allocated as high-speed cache), this external SSD delivers steady 10Gbps for transfers within the cache capacity
If you genuinely need remote administration, the firewall documentation describes changing the GUI listen address and allowing the corresponding traffic. A safer alternative is an authenticated SSH tunnel from the remote computer to the machine running Syncthing. Do not treat the sync port and the GUI port as interchangeable, and do not expose the GUI merely because two devices cannot synchronize.
Understand the privacy and security boundaries
What is protected
Syncthing’s Security Principles documentation states: “All device to device traffic is protected by TLS.” Device identity is checked using the certificate fingerprint represented by the human-readable Device ID. A relay therefore does not receive readable file contents simply because it forwards the connection.
What discovery services can learn
- Global discovery: the service receives device IDs, listening ports, and announcements. Those records can associate an ID with an external IP address. Disabling global discovery improves control over that metadata but can make peers with dynamic addresses outside your LAN harder to find.
- Local discovery: broadcasts or multicasts the device ID and listening port on the local network. Anyone able to observe that network may see those announcements. Disabling it can prevent automatic discovery of local devices whose addresses change.
- Relays: can see device IDs, IP addresses, and traffic volume. Relayed file data remains encrypted between the endpoints.
These details mean “private syncing” describes where the file copies are stored and who authorizes peers; it does not mean that Syncthing usage, device relationships, IP addresses, or transfer timing are invisible.
What’s actually slowing this PC down?
Pick the symptom - the matching free tool is one click away.
Protect keys and revoke lost devices
Anyone who gains access to a device’s Syncthing keys and configuration can impersonate that device and access files available to it. Protect the configuration directory with normal operating-system permissions and disk encryption. If a laptop or phone is lost, remove or revoke its device entry from every peer as soon as possible, then reassess any credentials stored on the lost device.
Encrypted folders for untrusted devices
Syncthing has an untrusted-device encrypted-folder feature marked beta/testing-only. It is intended to hide file data and names from a device that stores an encrypted representation, but it still exposes information such as the folder ID or label and file sizes. Do not use this experimental feature as a substitute for a mature backup and encryption plan for important data.
Why synchronization is not a backup
Syncthing propagates changes, including deletions. If you delete a file on one online device, that deletion can reach the others. If a file is encrypted by ransomware and the change synchronizes, every connected copy may be affected.
Rank #4
- Easily store and access 2TB to content on the go with the Seagate Portable Drive, a USB external hard drive
- Designed to work with Windows or Mac computers, this external hard drive makes backup a snap just drag and drop
- To get set up, connect the portable hard drive to a computer for automatic recognition no software required
- This USB drive provides plug and play simplicity with the included 18 inch USB 3.0 cable
- The available storage capacity may vary.
File versioning options
Versioning is off by default and is configured per folder and per device. It archives changes received from another device; it does not automatically archive a local edit made on the same device where that edit occurred.
Recommended Free Tools
| Strategy | Behavior | Use when |
|---|---|---|
| Trash Can | Keeps replaced or deleted files in a trash area according to the configured retention behavior. | You want simple protection against recent synchronized deletions. |
| Simple | Keeps a configured number of older versions. | You prefer a predictable count of retained copies. |
| Staggered | Retains versions using time-based intervals, preserving recent history more densely and older history more sparsely. | You need longer history without keeping every intermediate copy. |
Configure versioning on receiving peers where it is useful, then deliberately test a replacement and a deletion so you know where archived files appear and how retention behaves. Maintain a separate backup—such as an offline or otherwise independent copy—for data that must survive device failure, local overwrite, synchronized deletion, or compromise of the Syncthing configuration.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Troubleshoot devices that will not connect
1. Confirm both sides are actually paired
Compare the complete Device IDs in both GUIs. A device name is not proof of identity. Make sure each peer has added the other device, accepted any pending request, and saved the configuration.
2. Check the device status before changing settings
Look at the remote-device status in the GUI. “Disconnected” points to discovery, routing, firewall, or service problems; a connected device with a folder that is not syncing points more often to folder sharing, path, or permissions.
3. Verify the folder share and local path
Ensure the folder is shared with the intended peer on the source device and accepted on the destination. Check that the destination path exists, is mounted, and is writable by the account running Syncthing. Confirm that both sides use the same folder ID for that share.
4. Check firewalls and listening ports
Allow TCP 22000 and UDP 22000 as required by your chosen sync protocols, plus UDP 21027 for local discovery. Check host firewalls on both devices as well as router policies. If you configured a non-default sync port, use that value instead of assuming 22000.
Best Value
- NEARLY 2X FASTER THAN OUR PREVIOUS GENERATION(8) – move 1,000 high-res photos in under 60 seconds(6) with up to 2000MB/s transfer speeds(2).
- IP65 RATING AND UP TO 3M DROP PROTECTION(3) – protects against spills and drops.
- POCKET-SIZED – fits easily in pockets and small bags.
- SPACE TO OWN YOUR AI CONTENT – speed and capacity to download your high-res clips and photo edits.
- 256-BIT AES ENCRYPTION(4) – helps keep private files secure with password protection.
5. Distinguish direct connections from relay connections
A relay connection can be legitimate but slow. If the status shows a relay, test whether both networks permit a direct path and whether the sync port is reachable. Do not disable relays until you have another route; doing so can turn a slow synchronization into no synchronization.
6. Recheck time, sleep, and network changes
Both devices must be running and online together to exchange changes. Laptops that sleep, phones that suspend background work, VPN changes, captive portals, and switching between Wi-Fi and cellular networks can interrupt a previously working path. Bring both devices online, wait for discovery, and watch whether the connection returns before reconfiguring anything.
Using Syncthing with iPhone or iPad
The Syncthing project FAQ says there is no official iOS client and no foreseeable plan for one, largely because iOS background-processing limits make continuous synchronization difficult. Third-party applications exist. Möbius Sync is one such third-party iOS app and describes synchronization between iOS and other supported devices; its current App Store listing contains the authoritative availability, regional, pricing, and feature information.
Quick wins for a faster PC:
Repair Windows errors before they cause bigger problemsFix Now →Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Clear out junk files and repair common Windows errorsFree Scan →Because iOS can suspend background activity and app capabilities can change, treat an iPhone or iPad as a platform with different reliability characteristics from a desktop or server. Check the current app documentation for which folders are accessible, when synchronization runs, and whether paid capabilities are required. Do not assume that an iOS device will remain an always-on peer.
Practical operating patterns
Two computers that are often online
Share a narrowly defined working folder, keep both Syncthing services running, and enable versioning on at least one receiving peer. Test edits and deletions before moving important work into the share.
A laptop and an occasionally connected desktop
Expect changes to queue locally until the desktop is awake. Use versioning on the desktop if it is the safer receiving copy, and schedule an independent backup rather than relying on the desktop’s synchronized folder alone.
An always-on home host
An always-on computer or server can improve availability, but it is not automatically a backup. Protect its keys, limit the folders it shares, monitor disk capacity, and keep an independent copy that is not continuously writable by the sync process.
The Tool Desk
Outbyte PC Repair FREEClear out junk files and repair common Windows errorsFree Scan →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Quick Recap
Maintenance checklist
- Review the device list and remove peers you no longer control.
- Confirm every shared folder’s local path and available disk space.
- Check that versioning is enabled where you intended it and periodically test restoration.
- Keep the administration GUI local unless remote access is necessary and secured.
- Review firewall rules after changing networks, routers, VPNs, or sync ports.
- Maintain a separate backup with a recovery procedure you have actually tested.
- Revisit mobile-app compatibility and platform limits when an operating system or third-party client updates.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
