Index: autotests/src/katedocument_test.h
===================================================================
--- autotests/src/katedocument_test.h
+++ autotests/src/katedocument_test.h
@@ -37,25 +37,18 @@
     void testWordWrap();
     void testReplaceQStringList();
     void testMovingInterfaceSignals();
-
     void testSetTextPerformance();
     void testRemoveTextPerformance();
-
     void testForgivingApiUsage();
-
     void testRemoveMultipleLines();
     void testInsertNewline();
     void testInsertAfterEOF();
-
     void testReplaceTabs();
-
+    void testAutoBrackets();
     void testDigest();
     void testModelines();
-
     void testDefStyleNum();
-
     void testTypeCharsWithSurrogateAndNewLine();
-
     void testRemoveComposedCharacters();
 };
 
Index: autotests/src/katedocument_test.cpp
===================================================================
--- autotests/src/katedocument_test.cpp
+++ autotests/src/katedocument_test.cpp
@@ -280,6 +280,66 @@
     QVERIFY(doc.removeText(Range(0, 0, 0, 1000)));
 }
 
+void KateDocumentTest::testAutoBrackets()
+{
+    KTextEditor::DocumentPrivate doc;
+    auto view = static_cast<KTextEditor::ViewPrivate*>(doc.createView(nullptr));
+
+    auto reset = [&]() {
+        doc.setText("");
+        view->setCursorPosition(Cursor(0, 0));
+    };
+
+    auto typeText = [&](const QString &text) {
+        for (int i = 0; i < text.size(); ++i) {
+            doc.typeChars(view, text.at(i));
+        }
+    };
+
+    doc.setHighlightingMode ("Normal"); // Just to be sure
+    view->config()->setAutoBrackets(true);
+
+    QString testInput;
+
+    testInput = ("(");
+    typeText(testInput);
+    QCOMPARE(doc.text(), "()");
+
+    reset();
+    testInput = ("\"");
+    typeText(testInput);
+    QCOMPARE(doc.text(), "\"\"");
+
+    reset();
+    testInput = ("'");
+    typeText(testInput);
+    QCOMPARE(doc.text(), "'"); // In Normal mode there is only one quote to expect
+
+    //
+    // Switch over to some other mode
+    //
+    doc.setHighlightingMode ("C++");
+
+    reset();
+    typeText(testInput);
+    QCOMPARE(doc.text(), "''"); // Now it must be two
+
+    reset();
+    testInput = "('')";
+    typeText(testInput);
+    // Known bad behaviour in case of nested brackets
+    QCOMPARE(doc.text(), "(''))"); // FIXME/TODO should be "('')" like testInput
+
+    reset();
+    testInput = ("foo \"bar\" haz");
+    typeText(testInput);
+    QCOMPARE(doc.text(), testInput);
+    // Simulate afterwards to add quotes, bug 405089
+    doc.setText("foo \"bar");
+    typeText("\" haz");
+    QCOMPARE(doc.text(), testInput);
+}
+
 void KateDocumentTest::testReplaceTabs()
 {
     KTextEditor::DocumentPrivate doc;
Index: src/document/katedocument.cpp
===================================================================
--- src/document/katedocument.cpp
+++ src/document/katedocument.cpp
@@ -114,19 +114,17 @@
     return indexOf(list, entry) >= 0;
 }
 
-static inline QChar matchingStartBracket(QChar c, bool withQuotes)
+static inline QChar matchingStartBracket(const QChar c)
 {
     switch (c.toLatin1()) {
         case '}': return QLatin1Char('{');
         case ']': return QLatin1Char('[');
         case ')': return QLatin1Char('(');
-        case '\'': return withQuotes ? QLatin1Char('\'') : QChar();
-        case '"': return withQuotes ? QLatin1Char('"') : QChar();
     }
     return QChar();
 }
 
-static inline QChar matchingEndBracket(QChar c, bool withQuotes)
+static inline QChar matchingEndBracket(const QChar c, bool withQuotes = true)
 {
     switch (c.toLatin1()) {
         case '{': return QLatin1Char('}');
@@ -138,26 +136,26 @@
     return QChar();
 }
 
-static inline QChar matchingBracket(QChar c, bool withQuotes)
+static inline QChar matchingBracket(const QChar c)
 {
-    QChar bracket = matchingStartBracket(c, withQuotes);
+    QChar bracket = matchingStartBracket(c);
     if (bracket.isNull()) {
-        bracket = matchingEndBracket(c, false);
+        bracket = matchingEndBracket(c, /*withQuotes=*/false);
     }
     return bracket;
 }
 
-static inline bool isStartBracket(const QChar &c)
+static inline bool isStartBracket(const QChar c)
 {
-    return ! matchingEndBracket(c, false).isNull();
+    return ! matchingEndBracket(c, /*withQuotes=*/false).isNull();
 }
 
-static inline bool isEndBracket(const QChar &c)
+static inline bool isEndBracket(const QChar c)
 {
-    return ! matchingStartBracket(c, false).isNull();
+    return ! matchingStartBracket(c).isNull();
 }
 
-static inline bool isBracket(const QChar &c)
+static inline bool isBracket(const QChar c)
 {
     return isStartBracket(c) || isEndBracket(c);
 }
@@ -2957,16 +2955,17 @@
      */
     QChar closingBracket;
     if (view->config()->autoBrackets() && chars.size() == 1) {
+        const QChar typedChar = chars.at(0);
         /**
          * we inserted a bracket?
          * => remember the matching closing one
          */
-        closingBracket = matchingEndBracket(chars[0], true);
+        closingBracket = matchingEndBracket(typedChar);
 
         /**
          * closing bracket for the autobracket we inserted earlier?
          */
-        if ( m_currentAutobraceClosingChar == chars[0] && m_currentAutobraceRange ) {
+        if (m_currentAutobraceClosingChar == typedChar && m_currentAutobraceRange) {
             // do nothing
             m_currentAutobraceRange.reset(nullptr);
             view->cursorRight();
@@ -3059,15 +3058,30 @@
          * try to preserve the cursor position
          */
         bool skipAutobrace = closingBracket == QLatin1Char('\'');
-        if ( highlight() && skipAutobrace ) {
+        if (highlight() && skipAutobrace) {
             // skip adding ' in spellchecked areas, because those are text
             skipAutobrace = highlight()->spellCheckingRequiredForLocation(this, view->cursorPosition() - Cursor{0, 1});
         }
-        if (!closingBracket.isNull() && !skipAutobrace ) {
+
+        const auto cursorPos(view->cursorPosition());
+        if (!skipAutobrace && (closingBracket == QLatin1Char('\''))) {
+            // skip auto quotes when these looks already balanced, bug 405089
+            Kate::TextLine textLine = m_buffer->plainLine(cursorPos.line());
+            // RegEx match quote, but not excaped quote, thanks to https://stackoverflow.com/a/11819111
+            const int count = textLine->text().left(cursorPos.column()).count(QRegularExpression(QStringLiteral("(?<!\\\\)(?:\\\\\\\\)*\\\'")));
+            skipAutobrace = (count % 2 == 0) ? true : false;
+        }
+        if (!skipAutobrace && (closingBracket == QLatin1Char('\"'))) {
+            // ...same trick for double quotes
+            Kate::TextLine textLine = m_buffer->plainLine(cursorPos.line());
+            const int count = textLine->text().left(cursorPos.column()).count(QRegularExpression(QStringLiteral("(?<!\\\\)(?:\\\\\\\\)*\\\"")));
+            skipAutobrace = (count % 2 == 0) ? true : false;
+        }
+
+        if (!closingBracket.isNull() && !skipAutobrace) {
             // add bracket to the view
-            const auto cursorPos(view->cursorPosition());
             const auto nextChar = view->document()->text({cursorPos, cursorPos + Cursor{0, 1}}).trimmed();
-            if ( nextChar.isEmpty() || ! nextChar.at(0).isLetterOrNumber() ) {
+            if (nextChar.isEmpty() || !nextChar.at(0).isLetterOrNumber()) {
                 insertText(view->cursorPosition(), QString(closingBracket));
                 const auto insertedAt(view->cursorPosition());
                 view->setCursorPosition(cursorPos);
@@ -4065,7 +4079,7 @@
         return KTextEditor::Range::invalid();
     }
 
-    const QChar opposite = matchingBracket(bracket, false);
+    const QChar opposite = matchingBracket(bracket);
     if (opposite.isNull()) {
         return KTextEditor::Range::invalid();
     }