diff --git a/CHANGELOG.md b/CHANGELOG.md
index ca1822a..65d5b3c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ Common and useful classes, methods, exceptions etc.
 
 1. Tests > refactoring & minor improvements
 2. Utilities > CssSelector > useful methods related to CSS selectors
+3. Utilities > Bootstrap4CssSelector > useful methods related to CSS selectors and the Bootstrap4 (front-end component library)
 
 # 0.1.2
 
diff --git a/src/Utilities/Bootstrap4CssSelector.php b/src/Utilities/Bootstrap4CssSelector.php
new file mode 100644
index 0000000..6933274
--- /dev/null
+++ b/src/Utilities/Bootstrap4CssSelector.php
@@ -0,0 +1,85 @@
+<?php
+
+/**
+ * (c) Meritoo.pl, http://www.meritoo.pl
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Meritoo\Common\Utilities;
+
+/**
+ * Useful methods related to CSS selectors and the Bootstrap4 (front-end component library)
+ *
+ * @author    Meritoo <github@meritoo.pl>
+ * @copyright Meritoo <http://www.meritoo.pl>
+ */
+class Bootstrap4CssSelector
+{
+    /**
+     * Returns selector of container with field's validation error
+     *
+     * @return string
+     */
+    public static function getFieldErrorContainerSelector()
+    {
+        return '.invalid-feedback .form-error-message';
+    }
+
+    /**
+     * Returns selector of field's validation error
+     *
+     * @param string $formName Name of form (value of the "name" attribute)
+     * @param string $fieldId  ID of field (value of the "id" attribute)
+     * @return string
+     */
+    public static function getFieldErrorSelector($formName, $fieldId)
+    {
+        $labelSelector = CssSelector::getLabelSelector($formName, $fieldId);
+
+        if (empty($labelSelector)) {
+            return '';
+        }
+
+        $errorContainerSelector = static::getFieldErrorContainerSelector();
+
+        return sprintf('%s %s', $labelSelector, $errorContainerSelector);
+    }
+
+    /**
+     * Returns selector of radio-button's validation error
+     *
+     * @param string $formName      Name of form (value of the "name" attribute)
+     * @param int    $fieldSetIndex Index/Position of the field-set
+     * @return string
+     */
+    public static function getRadioButtonErrorSelector($formName, $fieldSetIndex)
+    {
+        $fieldSetSelector = CssSelector::getFieldSetByIndexSelector($formName, $fieldSetIndex);
+
+        if (empty($fieldSetSelector)) {
+            return '';
+        }
+
+        $errorContainerSelector = static::getFieldErrorContainerSelector();
+
+        return sprintf('%s legend.col-form-label %s', $fieldSetSelector, $errorContainerSelector);
+    }
+
+    /**
+     * Returns selector of field's group
+     *
+     * @param string $formName Name of form (value of the "name" attribute)
+     * @return string
+     */
+    public static function getFieldGroupSelector($formName)
+    {
+        $formSelector = CssSelector::getFormByNameSelector($formName);
+
+        if (empty($formSelector)) {
+            return '';
+        }
+
+        return sprintf('%s .form-group', $formSelector);
+    }
+}
diff --git a/tests/Utilities/Bootstrap4CssSelectorTest.php b/tests/Utilities/Bootstrap4CssSelectorTest.php
new file mode 100644
index 0000000..c2aa462
--- /dev/null
+++ b/tests/Utilities/Bootstrap4CssSelectorTest.php
@@ -0,0 +1,185 @@
+<?php
+
+/**
+ * (c) Meritoo.pl, http://www.meritoo.pl
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Meritoo\Common\Test\Utilities;
+
+use Meritoo\Common\Test\Base\BaseTestCase;
+use Meritoo\Common\Utilities\Bootstrap4CssSelector;
+
+/**
+ * Test case of the useful methods related to CSS selectors and the Bootstrap4 (front-end component library)
+ *
+ * @author    Meritoo <github@meritoo.pl>
+ * @copyright Meritoo <http://www.meritoo.pl>
+ */
+class Bootstrap4CssSelectorTest extends BaseTestCase
+{
+    public function testConstructor()
+    {
+        static::assertHasNoConstructor(Bootstrap4CssSelector::class);
+    }
+
+    /**
+     * @param string $emptyValue Name of form (value of the "name" attribute)
+     * @dataProvider provideEmptyScalarValue
+     */
+    public function testGetRadioButtonErrorSelectorUsingEmptyFormName($emptyValue)
+    {
+        $fieldSetIndex = 1;
+        static::assertSame('', Bootstrap4CssSelector::getRadioButtonErrorSelector($emptyValue, $fieldSetIndex));
+    }
+
+    public function testGetRadioButtonErrorSelectorUsingNegativeFieldSetIndex()
+    {
+        static::assertSame('', Bootstrap4CssSelector::getRadioButtonErrorSelector('test-test', -1));
+    }
+
+    /**
+     * @param string $formName      Name of form (value of the "name" attribute)
+     * @param int    $fieldSetIndex Index/Position of the field-set
+     * @param string $expected      Expected selector
+     *
+     * @dataProvider provideFormNameFieldSetIndexAndSelector
+     */
+    public function testGetRadioButtonErrorSelector($formName, $fieldSetIndex, $expected)
+    {
+        static::assertSame($expected, Bootstrap4CssSelector::getRadioButtonErrorSelector($formName, $fieldSetIndex));
+    }
+
+    /**
+     * @param string $emptyValue Name of form (value of the "name" attribute)
+     * @dataProvider provideEmptyScalarValue
+     */
+    public function testGetFieldErrorSelectorUsingEmptyFormName($emptyValue)
+    {
+        $fieldName = 'test';
+        static::assertSame('', Bootstrap4CssSelector::getFieldErrorSelector($emptyValue, $fieldName));
+    }
+
+    /**
+     * @param string $emptyValue Name of field (value of the "name" attribute)
+     * @dataProvider provideEmptyScalarValue
+     */
+    public function testGetFieldErrorSelectorUsingEmptyFieldName($emptyValue)
+    {
+        $formName = 'test';
+        static::assertSame('', Bootstrap4CssSelector::getFieldErrorSelector($formName, $emptyValue));
+    }
+
+    /**
+     * @param string $formName  Name of form (value of the "name" attribute)
+     * @param string $fieldName Name of field (value of the "name" attribute)
+     * @param string $expected  Expected selector
+     *
+     * @dataProvider provideFormNameFieldNameAndSelector
+     */
+    public function testGetFieldErrorSelector($formName, $fieldName, $expected)
+    {
+        static::assertSame($expected, Bootstrap4CssSelector::getFieldErrorSelector($formName, $fieldName));
+    }
+
+    /**
+     * @param string $emptyValue Name of form (value of the "name" attribute)
+     * @dataProvider provideEmptyScalarValue
+     */
+    public function testGetFieldGroupSelectorUsingEmptyFormName($emptyValue)
+    {
+        static::assertSame('', Bootstrap4CssSelector::getFieldGroupSelector($emptyValue));
+    }
+
+    /**
+     * @param string $formName Name of form (value of the "name" attribute)
+     * @param string $expected Expected selector
+     *
+     * @dataProvider provideFormNameAndSelector
+     */
+    public function testGetFieldGroupSelector($formName, $expected)
+    {
+        static::assertSame($expected, Bootstrap4CssSelector::getFieldGroupSelector($formName));
+    }
+
+    public function testGetFieldErrorContainerSelector()
+    {
+        static::assertSame('.invalid-feedback .form-error-message', Bootstrap4CssSelector::getFieldErrorContainerSelector());
+    }
+
+    /**
+     * Provides name of form, index/position of the field-set and expected selector
+     *
+     * @return \Generator
+     */
+    public function provideFormNameFieldSetIndexAndSelector()
+    {
+        yield[
+            'test',
+            0,
+            'form[name="test"] fieldset:nth-of-type(0) legend.col-form-label .invalid-feedback .form-error-message',
+        ];
+
+        yield[
+            'test-123-test-456',
+            1,
+            'form[name="test-123-test-456"] fieldset:nth-of-type(1) legend.col-form-label .invalid-feedback .form-error-message',
+        ];
+
+        yield[
+            'test_something_098_different',
+            1245,
+            'form[name="test_something_098_different"] fieldset:nth-of-type(1245) legend.col-form-label .invalid-feedback .form-error-message',
+        ];
+    }
+
+    /**
+     * Provides name of form, name of field and expected selector
+     *
+     * @return \Generator
+     */
+    public function provideFormNameFieldNameAndSelector()
+    {
+        yield[
+            'test',
+            'test',
+            'form[name="test"] label[for="test"] .invalid-feedback .form-error-message',
+        ];
+
+        yield[
+            'test-123-test-456',
+            'great-000-field',
+            'form[name="test-123-test-456"] label[for="great-000-field"] .invalid-feedback .form-error-message',
+        ];
+
+        yield[
+            'test_something_098_different',
+            'this-is-the-123789-field',
+            'form[name="test_something_098_different"] label[for="this-is-the-123789-field"] .invalid-feedback .form-error-message',
+        ];
+    }
+
+    /**
+     * Provides name of form and expected selector
+     *
+     * @return \Generator
+     */
+    public function provideFormNameAndSelector()
+    {
+        yield[
+            'test',
+            'form[name="test"] .form-group',
+        ];
+
+        yield[
+            'test-123-test-456',
+            'form[name="test-123-test-456"] .form-group',
+        ];
+
+        yield[
+            'test_something_098_different',
+            'form[name="test_something_098_different"] .form-group',
+        ];
+    }
+}