Syncthing-Fork

Syncthing is an open-source program that keeps folders in sync between your devices. In its documentation’s words, it “does not upload your data to the cloud but exchanges your data across your machines as soon as they are online at the same time”, and “All device to device traffic is protected by TLS.” Syncthing-Fork is an Android app built around it: it runs the official Syncthing program, version 2.1.7 in this file, in the background, and adds Android screens for folders and devices and rules for when syncing is allowed. You install Syncthing on your computer or other devices as well, and connect them by device ID or QR code.

Who makes it

Syncthing’s own Android app was discontinued; its README says “This app is discontinued. The last release on Github and F-Droid will happen with the December 2024 Syncthing version.” Syncthing-Fork, which had been forked from that app and maintained by a developer known as Catfriend1, carried on.

In November 2025 the project’s repository moved to a new maintainer, researchxxl. In February 2026, on Syncthing’s forum, Catfriend1 wrote: “I did hand over all my stuff to my inheritant @researchxxl inluding the com.github.catfriend1* apps, digital signing material”. Syncthing’s lead developer had criticised how it was done: “this is approximately the opposite of how I’d recommend doing one, in terms of communication and building trust.” Releases have continued about monthly since then, still signed with the “Catfriend1” certificate that the project’s wiki lists for its GitHub and F-Droid builds.

The Syncthing-Fork on Google Play is a separate release by another developer, nel0x, under the older package name. It doesn’t update this app, and this app doesn’t update it.

What it adds to Syncthing

• Android screens for folders, devices and status, so you don’t need Syncthing’s web interface. Devices are added by scanning their QR code with the built-in scanner, or picked from those found on the same network. The web interface is still there, but the wiki says it “should as far as possible be considered as read only”, because the app can overwrite changes made in it.
• Run conditions decide when Syncthing runs. Out of the box it runs on Wi-Fi or Ethernet, but not on metered Wi-Fi or mobile data; on battery as well as on the charger; and stops when Battery Saver is on. You can limit it to chosen Wi-Fi networks or to charging, follow a time schedule (by default 5 minutes in every hour, when switched on), and set exceptions for each folder or device.
• Folder types from Syncthing: send and receive, send only, receive only, and receive encrypted, plus versioning that keeps old or deleted files. New folders on the phone start with a trash can that keeps deleted files for 14 days.
• Extras: a list of recent changes, sharing files into a synced folder from other apps, Quick Settings tiles, settings export and import, Android TV support, and an optional “Syncthing Camera” that takes photos straight into a shared folder.

Our guide How to back up your Android photos to your computer walks through a one-way photo backup with it.

What goes online

• Your devices connect directly where they can. To find each other they use Syncthing’s defaults, all switched on: local discovery on your network; global discovery, which every 30 minutes sends your device ID and listening ports to Syncthing’s discovery servers; NAT traversal; and relays, which are used only when devices can’t connect directly. Relays can be run by anyone; they can’t read the files, but they learn your IP address and device ID. Each of these can be switched off in Settings › Syncthing Options.
• Usage reports stay off unless you agree. From three days after the first start, the app asks whether to allow “Anonymous Usage Reporting”.
• Crash reports: Syncthing’s crash-report setting is on by default, but this app starts Syncthing in a mode that skips the code that uploads them, so presumably none are sent. That is from reading the code; we haven’t checked it on a phone.
• No update checks: this build of Syncthing is compiled with its automatic upgrades turned off, and the app doesn’t look for updates itself.
• The web interface listens only on the phone itself (127.0.0.1:8384); access from other devices is a setting, off by default. The privacy policy: “The developer of the Syncthing-Fork Wrapper doesn’t have access to or gather any form of data from users of the application.”

Keeping it running

The first-run screens ask you to exempt the app from battery optimization; the wiki warns that “The app will cease to function if the permission is revoked.” A permanent notification keeps it running as a foreground service and can’t be turned off in the app. Autostart after a reboot is off by default (Settings › Behaviour). Some brands stop background apps anyway; the wiki has notes for Xiaomi, Huawei and Nokia phones.

The wiki also warns against syncing the Android/data, Android/media and WhatsApp folders: “Syncing constantly changing files like logs or databases is not supported. It may cause massive battery drain.”

About this file

• This is the developer’s own build of version 2.1.7.0, from the project’s GitHub releases (21 October 2026). F-Droid publishes the same developer-signed files once it has rebuilt them from source and confirmed they match, so updates from GitHub or F-Droid install over this one. On 22 October F-Droid offered 2.1.6.0.
• Since 2.1.6.0 the app includes the fix for a problem caused by Android’s September 2026 security patches: other apps, such as the KeePassDX password manager, lost access to a file whenever Syncthing replaced it. It asks for the new local network permission on Android 17, and 2.1.7.0 bundles Syncthing 2.1.7.
• One open issue: the “Run on metered Wi-Fi” condition can misjudge networks; a user reported the app refusing to run on an unmetered network with the message that it was “disallowed … to run on metered WiFi connections”.
• The 62.0 MB file runs on Android 6.0 and later, on ARM and x86, 32- and 64-bit. It asks for 19 permissions, including all files access (to sync any folder), location (only for Wi-Fi names) and the camera (for QR codes and Syncthing Camera). Our scan found no trackers.
• The screenshots are the project’s own, from 2019, and show an older version of the app.
• Syncthing-Fork and Syncthing are licensed under the MPL-2.0. The source of this version is at https://github.com/researchxxl/syncthing-android/tree/v2.1.7.0. It is smaller than 2.1.6.0 because this release turned on code and resource shrinking.

CPU types in this build: arm64-v8a (64-bit ARM, almost every phone since 2017); armeabi-v7a (32-bit ARM, older and budget phones); x86 (32-bit Intel, emulators); x86_64 (64-bit Intel, emulators and Chromebooks).

Recent releases on the project’s GitHub. We host and check only the newest one. Full changelog.