diff --git a/src/core/Database.cpp b/src/core/Database.cpp
index 9e01d3bc0..6dc971b33 100644
--- a/src/core/Database.cpp
+++ b/src/core/Database.cpp
@@ -282,6 +282,12 @@ void Database::recycleGroup(Group* group)
      }
 }
 
+void Database::merge(const Database* other)
+{
+    m_rootGroup->merge(other->rootGroup());
+    Q_EMIT modified();
+}
+
 void Database::setEmitModified(bool value)
 {
     if (m_emitModified && !value) {
diff --git a/src/core/Database.h b/src/core/Database.h
index 6fde3c601..6d2237d4c 100644
--- a/src/core/Database.h
+++ b/src/core/Database.h
@@ -105,6 +105,7 @@ public:
     void recycleGroup(Group* group);
     void setEmitModified(bool value);
     void copyAttributesFrom(const Database* other);
+    void merge(const Database* other);
 
     /**
      * Returns a unique id that is only valid as long as the Database exists.
diff --git a/src/core/Group.cpp b/src/core/Group.cpp
index 325ef9467..70260170a 100644
--- a/src/core/Group.cpp
+++ b/src/core/Group.cpp
@@ -32,6 +32,7 @@ Group::Group()
     m_data.isExpanded = true;
     m_data.autoTypeEnabled = Inherit;
     m_data.searchingEnabled = Inherit;
+    m_data.mergeMode = ModeInherit;
 }
 
 Group::~Group()
@@ -196,6 +197,19 @@ Group::TriState Group::searchingEnabled() const
     return m_data.searchingEnabled;
 }
 
+Group::MergeMode Group::mergeMode() const
+{
+    if (m_data.mergeMode == Group::MergeMode::ModeInherit) {
+        if (m_parent) {
+            return m_parent->mergeMode();
+        } else {
+            return Group::MergeMode::KeepNewer; // fallback
+        }
+    } else {
+        return m_data.mergeMode;
+    }
+}
+
 Entry* Group::lastTopVisibleEntry() const
 {
     return m_lastTopVisibleEntry;
@@ -303,6 +317,11 @@ void Group::setExpiryTime(const QDateTime& dateTime)
     }
 }
 
+void Group::setMergeMode(MergeMode newMode)
+{
+    set(m_data.mergeMode, newMode);
+}
+
 Group* Group::parentGroup()
 {
     return m_parent;
@@ -440,6 +459,18 @@ QList<Entry*> Group::entriesRecursive(bool includeHistoryItems) const
     return entryList;
 }
 
+Entry* Group::findEntry(const Uuid& uuid)
+{
+    Q_ASSERT(!uuid.isNull());
+    for (Entry* entry : asConst(m_entries)) {
+        if (entry->uuid() == uuid) {
+            return entry;
+        }
+    }
+
+    return nullptr;
+}
+
 QList<const Group*> Group::groupsRecursive(bool includeSelf) const
 {
     QList<const Group*> groupList;
@@ -490,6 +521,44 @@ QSet<Uuid> Group::customIconsRecursive() const
     return result;
 }
 
+void Group::merge(const Group* other)
+{
+    // merge entries
+    const QList<Entry*> dbEntries = other->entries();
+    for (Entry* entry : dbEntries) {
+        // entries are searched by uuid
+        if (!findEntry(entry->uuid())) {
+            entry->clone(Entry::CloneNoFlags)->setGroup(this);
+        } else {
+            resolveConflict(this->findEntry(entry->uuid()), entry);
+        }
+    }
+
+    // merge groups (recursively)
+    const QList<Group*> dbChildren = other->children();
+    for (Group* group : dbChildren) {
+        // groups are searched by name instead of uuid
+        if (this->findChildByName(group->name())) {
+            this->findChildByName(group->name())->merge(group);
+        } else {
+            group->setParent(this);
+        }
+    }
+
+    Q_EMIT modified();
+}
+
+Group* Group::findChildByName(const QString& name)
+{
+    for (Group* group : asConst(m_children)) {
+        if (group->name() == name) {
+            return group;
+        }
+    }
+
+    return nullptr;
+}
+
 Group* Group::clone(Entry::CloneFlags entryFlags) const
 {
     Group* clonedGroup = new Group();
@@ -624,6 +693,14 @@ void Group::recCreateDelObjects()
     }
 }
 
+void Group::markOlderEntry(Entry* entry)
+{
+    entry->attributes()->set(
+        "merged",
+        QString("older entry merged from database \"%1\"").arg(entry->group()->database()->metadata()->name())
+    );
+}
+
 bool Group::resolveSearchingEnabled() const
 {
     switch (m_data.searchingEnabled) {
@@ -663,3 +740,39 @@ bool Group::resolveAutoTypeEnabled() const
         return false;
     }
 }
+
+void Group::resolveConflict(Entry* existingEntry, Entry* otherEntry)
+{
+    const QDateTime timeExisting = existingEntry->timeInfo().lastModificationTime();
+    const QDateTime timeOther = otherEntry->timeInfo().lastModificationTime();
+
+    Entry* clonedEntry;
+
+    switch(this->mergeMode()) {
+        case KeepBoth:
+            // if one entry is newer, create a clone and add it to the group
+            if (timeExisting > timeOther) {
+                clonedEntry = otherEntry->clone(Entry::CloneNoFlags);
+                clonedEntry->setGroup(this);
+                this->markOlderEntry(clonedEntry);
+            } else if (timeExisting < timeOther) {
+                clonedEntry = otherEntry->clone(Entry::CloneNoFlags);
+                clonedEntry->setGroup(this);
+                this->markOlderEntry(existingEntry);
+            }
+            break;
+        case KeepNewer:
+            if (timeExisting < timeOther) {
+                // only if other entry is newer, replace existing one
+                this->removeEntry(existingEntry);
+                this->addEntry(otherEntry);
+            }
+
+            break;
+        case KeepExisting:
+            break;
+        default:
+            // do nothing
+            break;
+    }
+}
diff --git a/src/core/Group.h b/src/core/Group.h
index 3881ed246..025814b6c 100644
--- a/src/core/Group.h
+++ b/src/core/Group.h
@@ -34,6 +34,7 @@ class Group : public QObject
 
 public:
     enum TriState { Inherit, Enable, Disable };
+    enum MergeMode { ModeInherit, KeepBoth, KeepNewer, KeepExisting };
 
     struct GroupData
     {
@@ -46,6 +47,7 @@ public:
         QString defaultAutoTypeSequence;
         Group::TriState autoTypeEnabled;
         Group::TriState searchingEnabled;
+        Group::MergeMode mergeMode;
     };
 
     Group();
@@ -66,6 +68,7 @@ public:
     QString defaultAutoTypeSequence() const;
     Group::TriState autoTypeEnabled() const;
     Group::TriState searchingEnabled() const;
+    Group::MergeMode mergeMode() const;
     bool resolveSearchingEnabled() const;
     bool resolveAutoTypeEnabled() const;
     Entry* lastTopVisibleEntry() const;
@@ -74,6 +77,8 @@ public:
     static const int DefaultIconNumber;
     static const int RecycleBinIconNumber;
 
+    Entry* findEntry(const Uuid& uuid);
+    Group* findChildByName(const QString& name);
     void setUuid(const Uuid& uuid);
     void setName(const QString& name);
     void setNotes(const QString& notes);
@@ -87,6 +92,7 @@ public:
     void setLastTopVisibleEntry(Entry* entry);
     void setExpires(bool value);
     void setExpiryTime(const QDateTime& dateTime);
+    void setMergeMode(MergeMode newMode);
 
     void setUpdateTimeinfo(bool value);
 
@@ -113,6 +119,7 @@ public:
      */
     Group* clone(Entry::CloneFlags entryFlags = Entry::CloneNewUuid | Entry::CloneResetTimeInfo) const;
     void copyDataFrom(const Group* other);
+    void merge(const Group* other);
 
 Q_SIGNALS:
     void dataChanged(Group* group);
@@ -142,6 +149,8 @@ private:
     void addEntry(Entry* entry);
     void removeEntry(Entry* entry);
     void setParent(Database* db);
+    void markOlderEntry(Entry* entry);
+    void resolveConflict(Entry* existingEntry, Entry* otherEntry);
 
     void recSetDatabase(Database* db);
     void cleanupParent();
diff --git a/src/gui/DatabaseTabWidget.cpp b/src/gui/DatabaseTabWidget.cpp
index a5c5748c1..6e8a7b744 100644
--- a/src/gui/DatabaseTabWidget.cpp
+++ b/src/gui/DatabaseTabWidget.cpp
@@ -24,6 +24,7 @@
 
 #include "autotype/AutoType.h"
 #include "core/Config.h"
+#include "core/Global.h"
 #include "core/Database.h"
 #include "core/Group.h"
 #include "core/Metadata.h"
@@ -192,6 +193,21 @@ void DatabaseTabWidget::openDatabase(const QString& fileName, const QString& pw,
     }
 }
 
+void DatabaseTabWidget::mergeDatabase()
+{
+    QString filter = QString("%1 (*.kdbx);;%2 (*)").arg(tr("KeePass 2 Database"), tr("All files"));
+    const QString fileName = fileDialog()->getOpenFileName(this, tr("Merge database"), QString(),
+                                                       filter);
+    if (!fileName.isEmpty()) {
+        mergeDatabase(fileName);
+    }
+}
+
+void DatabaseTabWidget::mergeDatabase(const QString& fileName)
+{
+    currentDatabaseWidget()->switchToOpenMergeDatabase(fileName);
+}
+
 void DatabaseTabWidget::importKeePass1Database()
 {
     QString fileName = fileDialog()->getOpenFileName(this, tr("Open KeePass 1 database"), QString(),
diff --git a/src/gui/DatabaseTabWidget.h b/src/gui/DatabaseTabWidget.h
index 618b48b1c..7d095b560 100644
--- a/src/gui/DatabaseTabWidget.h
+++ b/src/gui/DatabaseTabWidget.h
@@ -55,6 +55,7 @@ public:
     ~DatabaseTabWidget();
     void openDatabase(const QString& fileName, const QString& pw = QString(),
                       const QString& keyFile = QString());
+    void mergeDatabase(const QString& fileName);
     DatabaseWidget* currentDatabaseWidget();
     bool hasLockableDatabases() const;
 
@@ -63,6 +64,7 @@ public:
 public Q_SLOTS:
     void newDatabase();
     void openDatabase();
+    void mergeDatabase();
     void importKeePass1Database();
     bool saveDatabase(int index = -1);
     bool saveDatabaseAs(int index = -1);
diff --git a/src/gui/DatabaseWidget.cpp b/src/gui/DatabaseWidget.cpp
index d97fc2f85..e330d99d0 100644
--- a/src/gui/DatabaseWidget.cpp
+++ b/src/gui/DatabaseWidget.cpp
@@ -118,6 +118,8 @@ DatabaseWidget::DatabaseWidget(Database* db, QWidget* parent)
     m_databaseSettingsWidget->setObjectName("databaseSettingsWidget");
     m_databaseOpenWidget = new DatabaseOpenWidget();
     m_databaseOpenWidget->setObjectName("databaseOpenWidget");
+    m_databaseOpenMergeWidget = new DatabaseOpenWidget();
+    m_databaseOpenMergeWidget->setObjectName("databaseOpenMergeWidget");
     m_keepass1OpenWidget = new KeePass1OpenWidget();
     m_keepass1OpenWidget->setObjectName("keepass1OpenWidget");
     m_unlockDatabaseWidget = new UnlockDatabaseWidget();
@@ -129,6 +131,7 @@ DatabaseWidget::DatabaseWidget(Database* db, QWidget* parent)
     addWidget(m_databaseSettingsWidget);
     addWidget(m_historyEditEntryWidget);
     addWidget(m_databaseOpenWidget);
+    addWidget(m_databaseOpenMergeWidget);
     addWidget(m_keepass1OpenWidget);
     addWidget(m_unlockDatabaseWidget);
 
@@ -147,6 +150,7 @@ DatabaseWidget::DatabaseWidget(Database* db, QWidget* parent)
     connect(m_changeMasterKeyWidget, SIGNAL(editFinished(bool)), SLOT(updateMasterKey(bool)));
     connect(m_databaseSettingsWidget, SIGNAL(editFinished(bool)), SLOT(switchToView(bool)));
     connect(m_databaseOpenWidget, SIGNAL(editFinished(bool)), SLOT(openDatabase(bool)));
+    connect(m_databaseOpenMergeWidget, SIGNAL(editFinished(bool)), SLOT(mergeDatabase(bool)));
     connect(m_keepass1OpenWidget, SIGNAL(editFinished(bool)), SLOT(openDatabase(bool)));
     connect(m_unlockDatabaseWidget, SIGNAL(editFinished(bool)), SLOT(unlockDatabase(bool)));
     connect(this, SIGNAL(currentChanged(int)), this, SLOT(emitCurrentModeChanged()));
@@ -663,6 +667,28 @@ void DatabaseWidget::openDatabase(bool accepted)
     }
 }
 
+void DatabaseWidget::mergeDatabase(bool accepted)
+{
+    if (accepted) {
+        if (!m_db) {
+            MessageBox::critical(this, tr("Error"), tr("No current database."));
+            return;
+        }
+
+        Database* srcDb = static_cast<DatabaseOpenWidget*>(sender())->database();
+
+        if (!srcDb) {
+            MessageBox::critical(this, tr("Error"), tr("No source database, nothing to do."));
+            return;
+        }
+
+        m_db->merge(srcDb);
+    }
+
+    setCurrentWidget(m_mainWidget);
+    Q_EMIT databaseMerged(m_db);
+}
+
 void DatabaseWidget::unlockDatabase(bool accepted)
 {
     if (!accepted) {
@@ -745,6 +771,19 @@ void DatabaseWidget::switchToOpenDatabase(const QString& fileName, const QString
     m_databaseOpenWidget->enterKey(password, keyFile);
 }
 
+void DatabaseWidget::switchToOpenMergeDatabase(const QString& fileName)
+{
+    m_databaseOpenMergeWidget->load(fileName);
+    setCurrentWidget(m_databaseOpenMergeWidget);
+}
+
+void DatabaseWidget::switchToOpenMergeDatabase(const QString& fileName, const QString& password,
+                                          const QString& keyFile)
+{
+    switchToOpenMergeDatabase(fileName);
+    m_databaseOpenMergeWidget->enterKey(password, keyFile);
+}
+
 void DatabaseWidget::switchToImportKeepass1(const QString& fileName)
 {
     updateFilename(fileName);
@@ -856,6 +895,12 @@ bool DatabaseWidget::isInSearchMode() const
     return m_entryView->inEntryListMode();
 }
 
+Group* DatabaseWidget::currentGroup() const
+{
+    return isInSearchMode() ? m_lastGroup
+                            : m_groupView->currentGroup();
+}
+
 void DatabaseWidget::clearLastGroup(Group* group)
 {
     if (group) {
@@ -956,3 +1001,11 @@ bool DatabaseWidget::currentEntryHasNotes()
     }
     return !currentEntry->notes().isEmpty();
 }
+
+GroupView* DatabaseWidget::groupView() {
+    return m_groupView;
+}
+
+EntryView* DatabaseWidget::entryView() {
+    return m_entryView;
+}
diff --git a/src/gui/DatabaseWidget.h b/src/gui/DatabaseWidget.h
index 571429036..8aa773fa2 100644
--- a/src/gui/DatabaseWidget.h
+++ b/src/gui/DatabaseWidget.h
@@ -62,6 +62,7 @@ public:
     bool canDeleteCurrentGroup() const;
     bool isInSearchMode() const;
     QString getCurrentSearch();
+    Group* currentGroup() const;
     int addWidget(QWidget* w);
     void setCurrentIndex(int index);
     void setCurrentWidget(QWidget* widget);
@@ -83,6 +84,8 @@ public:
     bool currentEntryHasPassword();
     bool currentEntryHasUrl();
     bool currentEntryHasNotes();
+    GroupView* groupView();
+    EntryView* entryView();
 
 Q_SIGNALS:
     void closeRequest();
@@ -90,6 +93,7 @@ Q_SIGNALS:
     void groupChanged();
     void entrySelectionChanged();
     void databaseChanged(Database* newDb);
+    void databaseMerged(Database* mergedDb);
     void groupContextMenuRequested(const QPoint& globalPos);
     void entryContextMenuRequested(const QPoint& globalPos);
     void unlockedDatabase();
@@ -116,12 +120,15 @@ public Q_SLOTS:
     void openUrlForEntry(Entry* entry);
     void createGroup();
     void deleteGroup();
+    void switchToView(bool accepted);
     void switchToEntryEdit();
     void switchToGroupEdit();
     void switchToMasterKeyChange();
     void switchToDatabaseSettings();
     void switchToOpenDatabase(const QString& fileName);
     void switchToOpenDatabase(const QString& fileName, const QString& password, const QString& keyFile);
+    void switchToOpenMergeDatabase(const QString& fileName);
+    void switchToOpenMergeDatabase(const QString& fileName, const QString& password, const QString& keyFile);
     void switchToImportKeepass1(const QString& fileName);
     // Search related slots
     void search(const QString& searchtext);
@@ -132,7 +139,6 @@ public Q_SLOTS:
 private Q_SLOTS:
     void entryActivationSignalReceived(Entry* entry, EntryModel::ModelColumn column);
     void switchBackToEntryEdit();
-    void switchToView(bool accepted);
     void switchToHistoryView(Entry* entry);
     void switchToEntryEdit(Entry* entry);
     void switchToEntryEdit(Entry* entry, bool create);
@@ -141,6 +147,7 @@ private Q_SLOTS:
     void emitEntryContextMenuRequested(const QPoint& pos);
     void updateMasterKey(bool accepted);
     void openDatabase(bool accepted);
+    void mergeDatabase(bool accepted);
     void unlockDatabase(bool accepted);
     void emitCurrentModeChanged();
     void clearLastGroup(Group* group);
@@ -158,6 +165,7 @@ private:
     ChangeMasterKeyWidget* m_changeMasterKeyWidget;
     DatabaseSettingsWidget* m_databaseSettingsWidget;
     DatabaseOpenWidget* m_databaseOpenWidget;
+    DatabaseOpenWidget* m_databaseOpenMergeWidget;
     KeePass1OpenWidget* m_keepass1OpenWidget;
     UnlockDatabaseWidget* m_unlockDatabaseWidget;
     QSplitter* m_splitter;
diff --git a/src/gui/MainWindow.cpp b/src/gui/MainWindow.cpp
index caac37974..54725a52a 100644
--- a/src/gui/MainWindow.cpp
+++ b/src/gui/MainWindow.cpp
@@ -213,6 +213,8 @@ MainWindow::MainWindow()
             SLOT(saveDatabaseAs()));
     connect(m_ui->actionDatabaseClose, SIGNAL(triggered()), m_ui->tabWidget,
             SLOT(closeDatabase()));
+    connect(m_ui->actionDatabaseMerge, SIGNAL(triggered()), m_ui->tabWidget,
+            SLOT(mergeDatabase()));
     connect(m_ui->actionChangeMasterKey, SIGNAL(triggered()), m_ui->tabWidget,
             SLOT(changeMasterKey()));
     connect(m_ui->actionChangeDatabaseSettings, SIGNAL(triggered()), m_ui->tabWidget,
@@ -378,6 +380,7 @@ void MainWindow::setMenuActionState(DatabaseWidget::Mode mode)
             m_ui->actionDatabaseSave->setEnabled(true);
             m_ui->actionDatabaseSaveAs->setEnabled(true);
             m_ui->actionExportCsv->setEnabled(true);
+            m_ui->actionDatabaseMerge->setEnabled(m_ui->tabWidget->currentIndex() != -1);
 
             m_searchWidgetAction->setEnabled(true);
             break;
@@ -405,6 +408,7 @@ void MainWindow::setMenuActionState(DatabaseWidget::Mode mode)
             m_ui->actionDatabaseSave->setEnabled(false);
             m_ui->actionDatabaseSaveAs->setEnabled(false);
             m_ui->actionExportCsv->setEnabled(false);
+            m_ui->actionDatabaseMerge->setEnabled(false);
 
             m_searchWidgetAction->setEnabled(false);
             break;
@@ -437,6 +441,7 @@ void MainWindow::setMenuActionState(DatabaseWidget::Mode mode)
         m_ui->actionDatabaseSaveAs->setEnabled(false);
         m_ui->actionDatabaseClose->setEnabled(false);
         m_ui->actionExportCsv->setEnabled(false);
+        m_ui->actionDatabaseMerge->setEnabled(false);
 
         m_searchWidgetAction->setEnabled(false);
     }
@@ -446,6 +451,7 @@ void MainWindow::setMenuActionState(DatabaseWidget::Mode mode)
     m_ui->actionDatabaseOpen->setEnabled(inDatabaseTabWidgetOrWelcomeWidget);
     m_ui->menuRecentDatabases->setEnabled(inDatabaseTabWidgetOrWelcomeWidget);
     m_ui->actionImportKeePass1->setEnabled(inDatabaseTabWidgetOrWelcomeWidget);
+    m_ui->actionDatabaseMerge->setEnabled(inDatabaseTabWidget);
     m_ui->actionRepairDatabase->setEnabled(inDatabaseTabWidgetOrWelcomeWidget);
 
     m_ui->actionLockDatabases->setEnabled(m_ui->tabWidget->hasLockableDatabases());
diff --git a/src/gui/MainWindow.ui b/src/gui/MainWindow.ui
index c9699ab2c..3cc2a67ea 100644
--- a/src/gui/MainWindow.ui
+++ b/src/gui/MainWindow.ui
@@ -119,6 +119,7 @@
     <addaction name="actionChangeMasterKey"/>
     <addaction name="actionChangeDatabaseSettings"/>
     <addaction name="separator"/>
+    <addaction name="actionDatabaseMerge"/>
     <addaction name="actionImportKeePass1"/>
     <addaction name="actionExportCsv"/>
     <addaction name="actionRepairDatabase"/>
@@ -243,6 +244,11 @@
     <string>&amp;New database</string>
    </property>
   </action>
+  <action name="actionDatabaseMerge">
+    <property name="text">
+      <string>Merge from KeePassX database</string>
+    </property>
+  </action>
   <action name="actionEntryNew">
    <property name="enabled">
     <bool>false</bool>
diff --git a/src/http/OptionDialog.ui b/src/http/OptionDialog.ui
index a230f2ad7..326507d51 100644
--- a/src/http/OptionDialog.ui
+++ b/src/http/OptionDialog.ui
@@ -201,7 +201,7 @@ Only entries with the same scheme (http://, https://, ftp://, ...) are returned<
         </widget>
        </item>
        <item>
-        <layout class="QHBoxLayout" name="horizontalLayout">
+        <layout class="QHBoxLayout" name="horizontalLayout_1">
          <item>
           <widget class="QLabel" name="label_5">
            <property name="sizePolicy">
@@ -225,7 +225,7 @@ Only entries with the same scheme (http://, https://, ftp://, ...) are returned<
         </layout>
        </item>
        <item>
-        <layout class="QHBoxLayout" name="horizontalLayout">
+        <layout class="QHBoxLayout" name="horizontalLayout_2">
          <item>
           <widget class="QLabel" name="label_4">
            <property name="sizePolicy">
diff --git a/tests/TestGroup.cpp b/tests/TestGroup.cpp
index e271abfc0..e87e6cedc 100644
--- a/tests/TestGroup.cpp
+++ b/tests/TestGroup.cpp
@@ -19,6 +19,7 @@
 
 #include <QPointer>
 #include <QSignalSpy>
+#include <QDebug>
 #include <QTest>
 
 #include "core/Database.h"
@@ -449,3 +450,120 @@ void TestGroup::testCopyCustomIcons()
     delete dbTarget;
     delete dbSource;
 }
+
+void TestGroup::testMerge()
+{
+    Group* group1 = new Group();
+    group1->setName("group 1");
+    Group* group2 = new Group();
+    group2->setName("group 2");
+
+    Entry* entry1 = new Entry();
+    Entry* entry2 = new Entry();
+
+    entry1->setGroup(group1);
+    entry1->setUuid(Uuid::random());
+    entry2->setGroup(group1);
+    entry2->setUuid(Uuid::random());
+
+    group2->merge(group1);
+
+    QCOMPARE(group1->entries().size(), 2);
+    QCOMPARE(group2->entries().size(), 2);
+}
+
+void TestGroup::testMergeDatabase()
+{
+    Database* dbSource = createMergeTestDatabase();
+    Database* dbDest = new Database();
+
+    dbDest->merge(dbSource);
+
+    QCOMPARE(dbDest->rootGroup()->children().size(), 2);
+    QCOMPARE(dbDest->rootGroup()->children().at(0)->entries().size(), 2);
+
+    delete dbDest;
+    delete dbSource;
+}
+
+void TestGroup::testMergeConflict()
+{
+    Database* dbSource = createMergeTestDatabase();
+
+    // test merging updated entries
+    // falls back to KeepBoth mode
+    Database* dbCopy = new Database();
+    dbCopy->setRootGroup(dbSource->rootGroup()->clone(Entry::CloneNoFlags));
+
+    // sanity check
+    QCOMPARE(dbCopy->rootGroup()->children().at(0)->entries().size(), 2);
+
+    // make this entry newer than in original db
+    Entry* updatedEntry = dbCopy->rootGroup()->children().at(0)->entries().at(0);
+    TimeInfo updatedTimeInfo = updatedEntry->timeInfo();
+    updatedTimeInfo.setLastModificationTime(updatedTimeInfo.lastModificationTime().addYears(1));
+    updatedEntry->setTimeInfo(updatedTimeInfo);
+
+    dbCopy->merge(dbSource);
+
+    // one entry is duplicated because of mode
+    QCOMPARE(dbCopy->rootGroup()->children().at(0)->entries().size(), 2);
+
+    delete dbSource;
+    delete dbCopy;
+}
+
+void TestGroup::testMergeConflictKeepBoth()
+{
+    Database* dbSource = createMergeTestDatabase();
+
+    // test merging updated entries
+    // falls back to KeepBoth mode
+    Database* dbCopy = new Database();
+    dbCopy->setRootGroup(dbSource->rootGroup()->clone(Entry::CloneNoFlags));
+
+    // sanity check
+    QCOMPARE(dbCopy->rootGroup()->children().at(0)->entries().size(), 2);
+
+    // make this entry newer than in original db
+    Entry* updatedEntry = dbCopy->rootGroup()->children().at(0)->entries().at(0);
+    TimeInfo updatedTimeInfo = updatedEntry->timeInfo();
+    updatedTimeInfo.setLastModificationTime(updatedTimeInfo.lastModificationTime().addYears(1));
+    updatedEntry->setTimeInfo(updatedTimeInfo);
+
+    dbCopy->rootGroup()->setMergeMode(Group::MergeMode::KeepBoth);
+
+    dbCopy->merge(dbSource);
+
+    // one entry is duplicated because of mode
+    QCOMPARE(dbCopy->rootGroup()->children().at(0)->entries().size(), 3);
+    // the older entry was merged from the other db as last in the group
+    Entry* olderEntry = dbCopy->rootGroup()->children().at(0)->entries().at(2);
+    QVERIFY2(olderEntry->attributes()->hasKey("merged"), "older entry is marked with an attribute \"merged\"");
+
+    delete dbSource;
+    delete dbCopy;
+}
+
+Database* TestGroup::createMergeTestDatabase()
+{
+    Database* db = new Database();
+
+    Group* group1 = new Group();
+    group1->setName("group 1");
+    Group* group2 = new Group();
+    group2->setName("group 2");
+
+    Entry* entry1 = new Entry();
+    Entry* entry2 = new Entry();
+
+    entry1->setGroup(group1);
+    entry1->setUuid(Uuid::random());
+    entry2->setGroup(group1);
+    entry2->setUuid(Uuid::random());
+
+    group1->setParent(db->rootGroup());
+    group2->setParent(db->rootGroup());
+
+    return db;
+}
diff --git a/tests/TestGroup.h b/tests/TestGroup.h
index c612a3ac6..4a891ae6f 100644
--- a/tests/TestGroup.h
+++ b/tests/TestGroup.h
@@ -19,6 +19,7 @@
 #define KEEPASSX_TESTGROUP_H
 
 #include <QObject>
+#include "core/Database.h"
 
 class TestGroup : public QObject
 {
@@ -33,6 +34,13 @@ private Q_SLOTS:
     void testCopyCustomIcon();
     void testClone();
     void testCopyCustomIcons();
+    void testMerge();
+    void testMergeConflict();
+    void testMergeDatabase();
+    void testMergeConflictKeepBoth();
+
+private:
+    Database* createMergeTestDatabase();
 };
 
 #endif // KEEPASSX_TESTGROUP_H
diff --git a/tests/data/MergeDatabase.kdbx b/tests/data/MergeDatabase.kdbx
new file mode 100644
index 000000000..f45929de2
Binary files /dev/null and b/tests/data/MergeDatabase.kdbx differ
diff --git a/tests/gui/TestGui.cpp b/tests/gui/TestGui.cpp
index b44491323..b25a09fdc 100644
--- a/tests/gui/TestGui.cpp
+++ b/tests/gui/TestGui.cpp
@@ -29,6 +29,7 @@
 #include <QToolBar>
 #include <QToolButton>
 #include <QTimer>
+#include <QSignalSpy>
 
 #include "config-keepassx-tests.h"
 #include "core/Config.h"
@@ -107,6 +108,37 @@ void TestGui::cleanup()
     m_dbWidget = nullptr;
 }
 
+void TestGui::testMergeDatabase()
+{
+    // this triggers a warning. Perhaps similar to https://bugreports.qt.io/browse/QTBUG-49623 ?
+    QSignalSpy dbMergeSpy(m_tabWidget->currentWidget(), SIGNAL(databaseMerged(Database*)));
+
+    // set file to merge from
+    fileDialog()->setNextFileName(QString(KEEPASSX_TEST_DATA_DIR).append("/MergeDatabase.kdbx"));
+    triggerAction("actionDatabaseMerge");
+
+    QWidget* databaseOpenMergeWidget = m_mainWindow->findChild<QWidget*>("databaseOpenMergeWidget");
+    QLineEdit* editPasswordMerge = databaseOpenMergeWidget->findChild<QLineEdit*>("editPassword");
+    QVERIFY(editPasswordMerge->isVisible());
+
+    m_tabWidget->currentDatabaseWidget()->setCurrentWidget(databaseOpenMergeWidget);
+
+    QTest::keyClicks(editPasswordMerge, "a");
+    QTest::keyClick(editPasswordMerge, Qt::Key_Enter);
+
+    QTRY_COMPARE(dbMergeSpy.count(), 1);
+    QTRY_VERIFY(m_tabWidget->tabText(m_tabWidget->currentIndex()).contains("*"));
+
+    m_db = m_tabWidget->currentDatabaseWidget()->database();
+
+    // there are seven child groups of the root group
+    QCOMPARE(m_db->rootGroup()->children().size(), 7);
+    // the merged group should contain an entry
+    QCOMPARE(m_db->rootGroup()->children().at(6)->entries().size(), 1);
+    // the General group contains one entry merged from the other db
+    QCOMPARE(m_db->rootGroup()->findChildByName("General")->entries().size(), 1);
+}
+
 void TestGui::testTabs()
 {
     QCOMPARE(m_tabWidget->count(), 1);
diff --git a/tests/gui/TestGui.h b/tests/gui/TestGui.h
index 72e3f4056..82ffc1850 100644
--- a/tests/gui/TestGui.h
+++ b/tests/gui/TestGui.h
@@ -38,6 +38,7 @@ private Q_SLOTS:
     void cleanup();
     void cleanupTestCase();
 
+    void testMergeDatabase();
     void testTabs();
     void testEditEntry();
     void testAddEntry();