diff --git a/build.gradle b/build.gradle
index d07a7f05..4d12ed7e 100644
--- a/build.gradle
+++ b/build.gradle
@@ -7,6 +7,7 @@ plugins {
     id "org.owasp.dependencycheck" version "7.1.2"
     id "com.diffplug.spotless" version "6.10.0"
     id 'jacoco'
+    id 'info.solidsoft.pitest' version '1.7.4'
     id 'se.patrikerdes.use-latest-versions' version '0.2.18'
     id 'com.github.ben-manes.versions' version '0.42.0'
 }
@@ -72,6 +73,8 @@ dependencies {
     testImplementation 'org.testcontainers:postgresql'
     testImplementation 'com.tngtech.archunit:archunit-junit5:1.0.0-rc1'
     testImplementation 'io.rest-assured:spring-mock-mvc'
+    testImplementation 'org.hamcrest:hamcrest-core:2.2'
+    testImplementation 'org.pitest:pitest-junit5-plugin:1.0.0'
 }
 
 dependencyManagement {
@@ -213,6 +216,36 @@ jacocoTestCoverageVerification {
     }
 }
 
+// pitest mutation testing
+pitest {
+    targetClasses = ['net.hostsharing.hsadminng.**']
+    excludedClasses = [
+            'net.hostsharing.hsadminng.config.**',
+            'net.hostsharing.hsadminng.generated.**'
+    ]
+
+    targetTests = ['net.hostsharing.hsadminng.**.*UnitTest', 'net.hostsharing.hsadminng.**.*RestTest']
+    excludedTestClasses = ['**AcceptanceTest*', '**IntegrationTest*']
+
+    pitestVersion = '1.9.0'
+    junit5PluginVersion = '1.0.0'
+
+    threads = 4
+
+    // As Java unit tests are pretty pointless in our case, this maybe makes not much sense.
+    mutationThreshold = 31
+    coverageThreshold = 44
+    testStrengthThreshold = 76
+
+    outputFormats = ['XML', 'HTML']
+    timestampedReports = false
+}
+project.tasks.check.dependsOn(project.tasks.pitest)
+project.tasks.pitest.doLast {
+    println "PiTest Mutation Report: file:///${project.rootDir}/build/reports/pitest/index.html"
+}
+
+
 // Dependency Versions Upgrade
 useLatestVersions {
     finalizedBy check
diff --git a/gradle.properties b/gradle.properties
index eca52c92..db7cb96e 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -3,9 +3,9 @@
 postgresql.version = 42.4.1
 
 # TODO: can be removed if all dependencies are JDK 16 compliant
-#org.gradle.jvmargs= \
-#  --add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
-#  --add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
-#  --add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
-#  --add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
-#  --add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
+org.gradle.jvmargs= \
+  --add-exports jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.file=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.parser=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.tree=ALL-UNNAMED \
+  --add-exports jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED
diff --git a/src/test/java/net/hostsharing/hsadminng/arch/ArchUnitTest.java b/src/test/java/net/hostsharing/hsadminng/arch/ArchTest.java
similarity index 89%
rename from src/test/java/net/hostsharing/hsadminng/arch/ArchUnitTest.java
rename to src/test/java/net/hostsharing/hsadminng/arch/ArchTest.java
index ec715867..2210d5e3 100644
--- a/src/test/java/net/hostsharing/hsadminng/arch/ArchUnitTest.java
+++ b/src/test/java/net/hostsharing/hsadminng/arch/ArchTest.java
@@ -1,7 +1,6 @@
 package net.hostsharing.hsadminng.arch;
 
 import com.tngtech.archunit.junit.AnalyzeClasses;
-import com.tngtech.archunit.junit.ArchTest;
 import com.tngtech.archunit.lang.ArchRule;
 import net.hostsharing.hsadminng.Accepts;
 import org.junit.jupiter.api.Test;
@@ -11,61 +10,61 @@ import org.springframework.web.bind.annotation.RestController;
 import static com.tngtech.archunit.lang.syntax.ArchRuleDefinition.*;
 import static com.tngtech.archunit.library.dependencies.SlicesRuleDefinition.slices;
 
-@AnalyzeClasses(packages = ArchUnitTest.NET_HOSTSHARING_HSADMINNG)
-public class ArchUnitTest {
+@AnalyzeClasses(packages = ArchTest.NET_HOSTSHARING_HSADMINNG)
+public class ArchTest {
 
     public static final String NET_HOSTSHARING_HSADMINNG = "net.hostsharing.hsadminng";
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule contextPackageRule = classes()
         .that().resideInAPackage("..context..")
         .should().onlyDependOnClassesThat()
         .resideOutsideOfPackage(NET_HOSTSHARING_HSADMINNG);
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule configPackageRule = classes()
         .that().resideInAPackage("..config..")
         .should().onlyDependOnClassesThat()
         .resideOutsideOfPackage(NET_HOSTSHARING_HSADMINNG);
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule errorsPackageRule = classes()
         .that().resideInAPackage("..errors..")
         .should().onlyDependOnClassesThat()
         .resideOutsideOfPackage(NET_HOSTSHARING_HSADMINNG);
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule hsPackagesRule = classes()
         .that().resideInAPackage("..hs.(*)..")
         .should().onlyBeAccessed().byClassesThat()
         .resideInAnyPackage("..hs.(*)..");
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule hsPackagePackageRule = classes()
         .that().resideInAPackage("..hs.hspackage..")
         .should().onlyBeAccessed().byClassesThat()
         .resideInAnyPackage("..hs.hspackage..");
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule acceptsAnnotationOnMethodsRule = methods()
         .that().areAnnotatedWith(Accepts.class)
         .should().beDeclaredInClassesThat().haveSimpleNameEndingWith("AcceptanceTest")
         .orShould().beDeclaredInClassesThat().haveSimpleNameNotContaining("AcceptanceTest$");
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule acceptsAnnotationOnClasesRule = classes()
         .that().areAnnotatedWith(Accepts.class)
         .should().haveSimpleNameEndingWith("AcceptanceTest")
         .orShould().haveSimpleNameNotContaining("AcceptanceTest$");
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule doNotUseJavaxTransactionAnnotationAtClassLevel = noClasses()
         .should().beAnnotatedWith(javax.transaction.Transactional.class.getName())
@@ -73,7 +72,7 @@ public class ArchUnitTest {
             org.springframework.transaction.annotation.Transactional.class.getName(),
             javax.transaction.Transactional.class));
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule doNotUseJavaxTransactionAnnotationAtMethodLevel = noMethods()
         .should().beAnnotatedWith(javax.transaction.Transactional.class)
@@ -81,7 +80,7 @@ public class ArchUnitTest {
             org.springframework.transaction.annotation.Transactional.class.getName(),
             javax.transaction.Transactional.class.getName()));
 
-    @ArchTest
+    @com.tngtech.archunit.junit.ArchTest
     @SuppressWarnings("unused")
     public static final ArchRule doNotUseOrgJUnitTestAnnotation = noMethods()
             .should().beAnnotatedWith(org.junit.Test.class)