Tray application and Dolphin/Plasma integration for Syncthing
C++ QML CMake Other
Clone or download
Latest commit af120f1 Aug 5, 2018

Syncthing Tray

  • Qt 5-based tray application
  • Dolphin/Plasma integration
  • command-line interface
  • Qt-ish C++ interface to control Syncthing

Supported platforms

  • Designed to work under any desktop environment supported by Qt 5 with tray icon support
  • No desktop environment specific libraries required (only for optional features)
  • Tested under *
    • Plasma 5 (native "Plasmoid" provided)
    • Openbox/qt5ct/Tint2
    • Awesome/qt5ct
    • Cinnamon
    • Windows 10
  • Can be shown as regular window if tray icon support is not available

* If you can confirm it works under other desktop environments, please add it to the list. Maybe someone could check whether it works under Mac OS X.


  • Provides quick access to most frequently used features but does not intend to replace the official web UI
    • Check state of directories and devices
    • Check current traffic statistics
    • Display further details about directories and devices, like last file, last scan, items out of sync, ...
    • Display ongoing downloads
    • Display Syncthing log
    • Trigger re-scan of a specific directory or all directories at once
    • Open a directory with the default file browser
    • Pause/resume a specific device or all devices at once
    • Pause/resume a specific directory
  • Shows Syncthing notifications
  • Can read the local Syncthing configuration file for quick setup when just connecting to local instance
  • Can show the status of the Syncthing systemd unit and allows to start and stop it (see section Use of systemd)
  • Provides an option to conveniently add the tray to the applications launched when the desktop environment starts
  • Can launch Syncthing and syncthing-inotify automatically when started and display stdout/stderr (useful under Windows)
  • Provides quick access to the official web UI
    • Utilizes either Qt WebKit or Qt WebEngine
    • Can be built without web view support as well (then the web UI is opened in the regular browser)
  • Allows quickly switching between multiple Syncthing instances
  • Shows notifications via Qt or uses D-Bus notification daemon directly
  • Also features a simple command line utility syncthingctl
    • Check Syncthing status
    • Trigger rescan/pause/resume/restart
    • Wait for idle
    • Supports Bash completion, even for directory and device names
  • Also bundles a KIO plugin which shows the status of a Syncthing directory and allows to trigger Syncthing actions in Dolphin file manager
    • Rescan selected items
    • Rescan entire Syncthing directory
    • Pause/resume Syncthing directory
    • See also screenshots section
  • Also has an (experimental) implementation as Plasmoid for Plasma 5 desktop
  • English and German localization

Planned features

The tray is still under development; the following features are under construction or planned:

  • Build Syncthing as a library to run it in the same process as the tray/GUI
  • Create Qt Quick Controls 2 and Kirigami 2 based frontend for mobile devices (focusing on Android)
  • Show recently processed items
  • Make some notifications configurable on folder level
  • Optionally notify for single file updates (


Under Openbox/Tint2


Under Plasma 5

Plasma 5 (Plasmoid) Plasma 5 (Plasmoid and Dolphin integration) Plasma 5 (regular GUI) Plasma 5 (directory error) Plasma 5 (dark)

Settings dialog

Settings dialog

Web view

Web view Web view (dark)

Syncthing actions for Dolphin



To create hotkeys, you can use the same approach as for any other application. Just make it invoke the syncthingctl application with the arguments for the desired action.

Hotkey for web UI

Just add --webui to the syncthingtray arguments to trigger the web UI. Syncthing Tray ensures that no second instance will be spawned if it is already running and just trigger the web UI.

Use of systemd

Use of systemd can be explicitely enabled/disabled by adding -DSYSTEMD_SUPPORT=ON/OFF to the CMake arguments. There will be no hard dependency to systemd in any case.

With systemd support the tray can start and stop the systemd unit of Syncthing. It will also take the unit status into account when connecting to the local instance. So connection attempts can be prevented when Syncthing isn't running anyways. However, those features are optional. To use them they must be enabled in the settings dialog first.

Note that this only works when starting Syncthing as user service. This is described in the Arch Wiki.



See the release section on GitHub.

Packages and binaries

Build instructions

The application depends on c++utilities and qtutilities and is built the same way as these libaries. For basic instructions checkout the README file of c++utilities. For building this straight, see the section above.

Further dependencies

The following Qt 5 modules are requried (version 5.6 or newer): core network dbus gui widgets svg webenginewidgets/webkitwidgets

The built-in web view is optional (see section "Select Qt module for WebView").

To build the plugin for Dolphin integration KIO is also requried. Additionally, the Dolphin plugin requires Qt 5.8 or newer. To skip building the plugin, add -DNO_FILE_ITEM_ACTION_PLUGIN:BOOL=ON to the CMake arguments.

To build the Plasmoid for the Plasma 5 desktop, the Qt 5 module QML and the KF5 module Plasma are required as well. Additionally, the Plasmoid requires Qt 5.8 or newer. To skip building the Plasmoid, add -DNO_PLASMOID:BOOL=ON to the CMake arguments.

It is also possible to build only the CLI (syncthingctl) by adding -DNO_MODEL:BOOL=ON and -DNO_FILE_ITEM_ACTION_PLUGIN:BOOL=ON to the CMake arguments. Then only the Qt modules core, network and dbus are required.

To get rid of systemd support, add -DENABLE_SYSTEMD_SUPPORT_BY_DEFAULT to the CMake arguments. In this case the Qt module D-Bus is not required anymore. Note that there is no hard dependency to systemd in any case.

Building the testsuite requires CppUnit and Qt 5.8 or higher.

Building this straight

  1. Install (preferably the latest version of) g++ or clang, the required Qt 5 modules and CMake.
  2. Get the sources. For the lastest version from Git clone the following repositories:
    cd $SOURCES
    git clone c++utilities
    git clone
    git clone
    git clone
  3. Build and install everything in one step:
    cd $BUILD_DIR
    cmake \
     -DCMAKE_BUILD_TYPE=Release \
     -DCMAKE_INSTALL_PREFIX="/install/prefix" \
    make install -j$(nproc)

Select Qt module for WebView

  • If Qt WebKitWidgets is installed on the system, the tray will link against it. Otherwise it will link against Qt WebEngineWidgets.
  • To force usage of Qt WebKit/Qt WebEngine or to disable both add -DWEBVIEW_PROVIDER=webkit/webengine/none to the CMake arguments.
  • To use Qt WebKit revived/ng, set the web view provider to webkit. It works already without any (known) issues.

BTW: I still prefer the deprecated Qt WebKit because

  • Currently there is no way to allow a particular self-signed certificate in Qt WebEngine. Currently any self-signed certificate is accepted! See:
  • Qt WebEngine can not be built with mingw-w64.
  • QWebEngineView seems to eat keyPressEvent.
  • Qt WebEngine is more buggy in my experience.
  • Security issues are not a concern because no other website than the Syncthing web UI is shown. Any external links will be opened in the regular web browser anyways.
  • It will be replaced by the compatible Qt WebKit revived/ng soon and hence no longer be deprecated.


Adding translations

Currently translations for English and German are available. Further translations can be added quite easily:

  1. Append a new translation file for the desired locale to the TS_FILES list in connector/CMakeLists.txt, model/CMakeLists.txt, widgets/CMakeLists.txt, plasmoid/CMakeLists.txt and tray/CMakeLists.txt.
  2. Trigger a new build, eg. follow steps under Building this straight.
  3. New translation files should have been created by the build system under connector/translations, model/translations and tray/translations.
  4. Open the files with Qt Linguist to add translations. Qt Linguist is part of the Qt Tools repository and its usage is well documented.

Note that the CLI syncthingctl currently does not support translations.

Using backend libraries

The contained backend libraries (which provide connecting to Syncthing, data models and more) are written for internal use whithin the components contained by this repository.

Hence those libraries do not provide a stable ABI/API. If you like to use them to develop Syncthing integration or tooling with Qt and C++, it makes most sense to contribute it as an additional component directly to this repository. Then I will be able to take it into account when changeing the API.

KDE integration

Since the Dolphin integration and the Plasmoid are plugins, testing and debugging requires a few extra steps. See Testing and debugging Dolphin/KIO plugin with Qt Creator and Testing and debugging Plasma 5 plasmoid with Qt Creator.

Known bugs

The following bugs are caused by dependencies and hence tracked externally. For bugs of Syncthing Tray itself, checkout the issues on GitHub.