diff --git a/CMakeLists.txt b/CMakeLists.txt
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -41,6 +41,7 @@
     Archive
     Config
     CoreAddons
+    DBusAddons
     Declarative
     Holidays
     I18n
@@ -76,6 +77,7 @@
 ################# list the subdirectories #################
 add_subdirectory(applets)
 add_subdirectory(dataengines)
+add_subdirectory(kdeds)
 add_subdirectory(runners)
 
 add_subdirectory(wallpapers)
diff --git a/dataengines/potd/PoTD-list.txt b/dataengines/potd/PoTD-list.txt
--- a/dataengines/potd/PoTD-list.txt
+++ b/dataengines/potd/PoTD-list.txt
@@ -5,6 +5,7 @@
 http://antwrp.gsfc.nasa.gov/apod/astropix.html
 Each day can be reached via the URL http://antwrp.gsfc.nasa.gov/apod/apYYMMDD.html
 where YY is the 2 digits year, MM is the 2 digits month and DD is the 2 digits day.
+Note: sometimes, the webpage shows a YouTube video and picture cannot be fetched.
 
 * Flickr Interestingness  ----------------------------  DONE
 http://www.flickr.com/explore/interesting/
diff --git a/dataengines/potd/cachedprovider.cpp b/dataengines/potd/cachedprovider.cpp
--- a/dataengines/potd/cachedprovider.cpp
+++ b/dataengines/potd/cachedprovider.cpp
@@ -1,10 +1,10 @@
 /*
  *   Copyright (C) 2007 Tobias Koenig <tokoe@kde.org>
  *
- *   This program is free software; you can redistribute it and/or modify  
- *   it under the terms of the GNU General Public License as published by  
- *   the Free Software Foundation; either version 2 of the License, or     
- *   (at your option) any later version.   
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
  *
  *   This program is distributed in the hope that it will be useful,
  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -51,13 +51,13 @@
 void SaveImageThread::run()
 {
     const QString path = CachedProvider::identifierToPath( m_identifier );
-    m_image.save(path, "PNG");
+    m_image.save(path, "JPEG");
     emit done( m_identifier, path, m_image );
 }
 
 QString CachedProvider::identifierToPath( const QString &identifier )
 {
-    const QString dataDir = QStandardPaths::writableLocation(QStandardPaths::CacheLocation) + QLatin1String("/plasma_engine_potd/");
+    const QString dataDir = QStandardPaths::writableLocation(QStandardPaths::TempLocation) + QLatin1String("/plasma_engine_potd/");
     QDir d;
     d.mkpath(dataDir);
     return dataDir + identifier;
@@ -98,7 +98,7 @@
     if (!QFile::exists( path ) ) {
         return false;
     }
-    
+
     QRegularExpression re(QLatin1String(":\\d{4}-\\d{2}-\\d{2}"));
 
     if (!ignoreAge && !re.match(identifier).hasMatch()) {
diff --git a/kdeds/CMakeLists.txt b/kdeds/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/kdeds/CMakeLists.txt
@@ -0,0 +1 @@
+add_subdirectory(potd)
diff --git a/kdeds/potd/CMakeLists.txt b/kdeds/potd/CMakeLists.txt
new file mode 100644
--- /dev/null
+++ b/kdeds/potd/CMakeLists.txt
@@ -0,0 +1,16 @@
+########### next target ###############
+
+set(dbus_interface_name org.kde.potd.xml)
+set(kded_potd_PART_SRCS kded_potd.cpp)
+
+add_library(kded_potd MODULE ${kded_potd_PART_SRCS})
+set_target_properties(kded_potd PROPERTIES OUTPUT_NAME potd)
+
+target_link_libraries(kded_potd
+   KF5::DBusAddons
+   KF5::Plasma
+)
+
+########### install files ###############
+kcoreaddons_desktop_to_json(kded_potd kded_potd.desktop)
+install(TARGETS kded_potd DESTINATION ${PLUGIN_INSTALL_DIR}/kf5/kded)
diff --git a/kdeds/potd/README.md b/kdeds/potd/README.md
new file mode 100644
--- /dev/null
+++ b/kdeds/potd/README.md
@@ -0,0 +1,8 @@
+# Picture Of The Day (POTD) Caching Daemon
+
+The lock screen runs in a special mode where it cannot access the internet. So
+when it trys to load a POTD wallpaper that isn't cached, it fails.
+
+This daemon caches POTD before screen locking. The lock screen always loads POTD
+from cache. Whenever the lock screen configuration changes, the daemon will read
+the configuration and cache POTD if necessary.
diff --git a/kdeds/potd/kded_potd.h b/kdeds/potd/kded_potd.h
new file mode 100644
--- /dev/null
+++ b/kdeds/potd/kded_potd.h
@@ -0,0 +1,35 @@
+#ifndef _KDED_POTD_H_
+#define _KDED_POTD_H_
+
+#include <QObject>
+#include <QString>
+#include <QFileSystemWatcher>
+
+#include <KConfig>
+#include <KConfigGroup>
+#include <KDEDModule>
+#include <Plasma/DataEngine>
+#include <Plasma/DataEngineConsumer>
+
+class PotdModule: public KDEDModule
+{
+    Q_OBJECT
+
+public:
+    PotdModule(QObject* parent, const QList<QVariant>&);
+    virtual ~PotdModule();
+
+private Q_SLOTS:
+    void fileChanged(const QString &path);
+
+private:
+    QString getSource();
+
+    Plasma::DataEngineConsumer *consumer;
+    Plasma::DataEngine *engine;
+    QFileSystemWatcher *watcher;
+    QString configPath;
+    QString previousSource;
+};
+
+#endif
diff --git a/kdeds/potd/kded_potd.cpp b/kdeds/potd/kded_potd.cpp
new file mode 100644
--- /dev/null
+++ b/kdeds/potd/kded_potd.cpp
@@ -0,0 +1,61 @@
+#include "kded_potd.h"
+
+#include <KPluginFactory>
+
+K_PLUGIN_CLASS_WITH_JSON(PotdModule, "kded_potd.json")
+
+PotdModule::PotdModule(QObject* parent, const QList<QVariant>&): KDEDModule(parent)
+{
+    consumer = new Plasma::DataEngineConsumer();
+    engine = consumer->dataEngine(QStringLiteral("potd"));
+    configPath = QStandardPaths::locate(QStandardPaths::ConfigLocation,  QStringLiteral("kscreenlockerrc"));
+
+    previousSource = getSource();
+    engine->connectSource(previousSource, this); // trigger caching, no need to handle data
+
+    watcher = new QFileSystemWatcher(this);
+    watcher->addPath(configPath);
+    connect(watcher, &QFileSystemWatcher::fileChanged, this, &PotdModule::fileChanged);
+}
+
+PotdModule::~PotdModule()
+{
+    delete consumer;
+}
+
+void PotdModule::fileChanged(const QString &path)
+{
+    Q_UNUSED(path);
+    engine->disconnectSource(previousSource, this);
+    previousSource = getSource();
+    engine->connectSource(previousSource, this);
+
+    // For some reason, Qt *rc files are always recreated instead of modified.
+    // Recreated files were removed from watchers and have to be added again.
+    watcher->addPath(configPath);
+}
+
+QString PotdModule::getSource()
+{
+    KConfig config(configPath);
+
+    KConfigGroup greeterGroup = config.group(QStringLiteral("Greeter"));
+    QString plugin = greeterGroup.readEntry(QStringLiteral("WallpaperPlugin"), QString());
+    if (plugin != QStringLiteral("org.kde.potd")) {
+        return QStringLiteral("");
+    }
+
+    KConfigGroup potdGroup = greeterGroup
+                               .group(QStringLiteral("Wallpaper"))
+                               .group(QStringLiteral("org.kde.potd"))
+                               .group(QStringLiteral("General"));
+    QString provider = potdGroup.readEntry(QStringLiteral("Provider"), QString());
+    if (provider == QStringLiteral("unsplash")) {
+        QString category = potdGroup.readEntry(QStringLiteral("Category"), QString());
+        return provider + QStringLiteral(":") + category;
+    } else {
+        return provider;
+    }
+}
+
+#include "kded_potd.moc"
diff --git a/kdeds/potd/kded_potd.desktop b/kdeds/potd/kded_potd.desktop
new file mode 100644
--- /dev/null
+++ b/kdeds/potd/kded_potd.desktop
@@ -0,0 +1,8 @@
+[Desktop Entry]
+Name=Picture of The Day
+Comment=Cache picture of the day for lock screen and SDDM
+Type=Service
+X-KDE-ServiceTypes=KDEDModule
+X-KDE-Library=potd
+X-KDE-Kded-autoload=true
+OnlyShowIn=KDE;