diff --git a/annotations/src/main/java/com/siimkinks/sqlitemagic/annotation/Database.java b/annotations/src/main/java/com/siimkinks/sqlitemagic/annotation/Database.java
index 94fd4cc..eaf53bd 100644
--- a/annotations/src/main/java/com/siimkinks/sqlitemagic/annotation/Database.java
+++ b/annotations/src/main/java/com/siimkinks/sqlitemagic/annotation/Database.java
@@ -31,4 +31,11 @@
    * @return List of submodules database configurations.
    */
   Class<?>[] submodules() default {};
+
+  /**
+   * Transformers from external modules.
+   *
+   * @return External transformers containing classes
+   */
+  Class<?>[] externalTransformers() default {};
 }
diff --git a/annotations/src/main/java/com/siimkinks/sqlitemagic/annotation/SubmoduleDatabase.java b/annotations/src/main/java/com/siimkinks/sqlitemagic/annotation/SubmoduleDatabase.java
index d90eac1..8853b27 100644
--- a/annotations/src/main/java/com/siimkinks/sqlitemagic/annotation/SubmoduleDatabase.java
+++ b/annotations/src/main/java/com/siimkinks/sqlitemagic/annotation/SubmoduleDatabase.java
@@ -17,4 +17,11 @@
    * @return Submodule name
    */
   String value();
+
+  /**
+   * Transformers from external modules.
+   *
+   * @return External transformers containing classes
+   */
+  Class<?>[] externalTransformers() default {};
 }
diff --git a/buildsystem/dependencies.gradle b/buildsystem/dependencies.gradle
index 4343b5c..9578203 100644
--- a/buildsystem/dependencies.gradle
+++ b/buildsystem/dependencies.gradle
@@ -15,7 +15,7 @@ ext {
   compileSdkVersion = 27
   targetSdkVersion = compileSdkVersion
 
-  androidGradleVersion = '3.2.0-alpha09'
+  androidGradleVersion = '3.2.0-alpha10'
   androidSupportLibsVersion = '27.1.0'
   androidVersion = '4.0.1.2' // do not increment!
   autoCommonVersion = '0.10'
diff --git a/compiler-core/src/main/java/com/siimkinks/sqlitemagic/Environment.java b/compiler-core/src/main/java/com/siimkinks/sqlitemagic/Environment.java
index e1459dd..365d846 100644
--- a/compiler-core/src/main/java/com/siimkinks/sqlitemagic/Environment.java
+++ b/compiler-core/src/main/java/com/siimkinks/sqlitemagic/Environment.java
@@ -18,6 +18,7 @@
 import com.siimkinks.sqlitemagic.element.TableElement;
 import com.siimkinks.sqlitemagic.element.TransformerElement;
 import com.siimkinks.sqlitemagic.element.ViewElement;
+import com.siimkinks.sqlitemagic.util.ConditionCallback;
 import com.siimkinks.sqlitemagic.util.Dual;
 import com.squareup.javapoet.TypeName;
 
@@ -130,7 +131,7 @@ public Environment(Messager messager, Elements elementUtils, Types typeUtils, Fi
 
   private void addDefaultTransformers() {
     for (String transformerName : Const.DEFAULT_TRANSFORMERS) {
-      final TransformerElement transformer = new TransformerElement(this);
+      final TransformerElement transformer = new TransformerElement(this, false);
       final Element transformerElement = elementUtils.getTypeElement(transformerName);
       for (Element enclosedElement : transformerElement.getEnclosedElements()) {
         if (enclosedElement.getKind() == ElementKind.METHOD) {
@@ -443,8 +444,18 @@ public ImmutableSet<ExecutableElement> getLocalAndInheritedColumnMethods(TypeEle
 
   @NonNull
   public Set<ExecutableElement> getLocalAndInheritedMethods(TypeElement type) {
+    return getLocalAndInheritedMethods(type, new ConditionCallback<ExecutableElement>() {
+      @Override
+      public boolean call(ExecutableElement method) {
+        return !method.getModifiers().contains(Modifier.STATIC);
+      }
+    });
+  }
+
+  @NonNull
+  public Set<ExecutableElement> getLocalAndInheritedMethods(TypeElement type, ConditionCallback<ExecutableElement> includeMethodCallback) {
     SetMultimap<String, ExecutableElement> methodMap = LinkedHashMultimap.create();
-    getLocalAndInheritedMethods(getPackage(type), type, methodMap);
+    getLocalAndInheritedMethods(getPackage(type), type, methodMap, includeMethodCallback);
     // Find methods that are overridden. We do this using `Elements.overrides`, which means
     // that it is inherently a quadratic operation, since we have to compare every method against
     // every other method. We reduce the performance impact by (a) grouping methods by name, since
@@ -472,21 +483,22 @@ public Set<ExecutableElement> getLocalAndInheritedMethods(TypeElement type) {
 
   private static void getLocalAndInheritedMethods(PackageElement pkg,
                                                   TypeElement type,
-                                                  SetMultimap<String, ExecutableElement> methods) {
+                                                  SetMultimap<String, ExecutableElement> methods,
+                                                  ConditionCallback<ExecutableElement> includeMethodCallback) {
     for (TypeMirror superInterface : type.getInterfaces()) {
       final TypeElement superInterfaceElement = asTypeElement(superInterface);
       final String interfaceName = superInterfaceElement.getSimpleName().toString();
       if (interfaceName.startsWith("Parcelable")) continue;
 
-      getLocalAndInheritedMethods(pkg, superInterfaceElement, methods);
+      getLocalAndInheritedMethods(pkg, superInterfaceElement, methods, includeMethodCallback);
     }
     if (type.getSuperclass().getKind() != TypeKind.NONE) {
       // Visit the superclass after superinterfaces so we will always see the implementation of a
       // method after any interfaces that declared it.
-      getLocalAndInheritedMethods(pkg, asTypeElement(type.getSuperclass()), methods);
+      getLocalAndInheritedMethods(pkg, asTypeElement(type.getSuperclass()), methods, includeMethodCallback);
     }
     for (ExecutableElement method : ElementFilter.methodsIn(type.getEnclosedElements())) {
-      if (!method.getModifiers().contains(Modifier.STATIC)
+      if (includeMethodCallback.call(method)
           && visibleFromPackage(method, pkg)) {
         methods.put(method.getSimpleName().toString(), method);
       }
diff --git a/compiler-core/src/main/java/com/siimkinks/sqlitemagic/element/TransformerElement.java b/compiler-core/src/main/java/com/siimkinks/sqlitemagic/element/TransformerElement.java
index 0b9218e..991550b 100644
--- a/compiler-core/src/main/java/com/siimkinks/sqlitemagic/element/TransformerElement.java
+++ b/compiler-core/src/main/java/com/siimkinks/sqlitemagic/element/TransformerElement.java
@@ -26,6 +26,8 @@
 
 public class TransformerElement {
   private final Environment environment;
+  @Getter
+  private final boolean external;
 
   private TypeElement deserializedTypeTransformerElement;
   private ClassName deserializedTypeTransformerClassName;
@@ -48,20 +50,23 @@ public class TransformerElement {
   private boolean hasObjectToDb = false;
   private boolean hasDbToObject = false;
 
-  public TransformerElement(Environment environment) {
+  public TransformerElement(Environment environment, boolean external) {
     this.environment = environment;
+    this.external = external;
   }
 
   public static TransformerElement fromObjectToDbValue(Environment environment,
-                                                       ExecutableElement objectToDbValue) {
-    final TransformerElement transformer = new TransformerElement(environment);
+                                                       ExecutableElement objectToDbValue,
+                                                       boolean external) {
+    final TransformerElement transformer = new TransformerElement(environment, external);
     transformer.addObjectToDbValueMethod(objectToDbValue);
     return transformer;
   }
 
   public static TransformerElement fromDbValueToObject(Environment environment,
-                                                       ExecutableElement dbValueToObject) {
-    final TransformerElement transformer = new TransformerElement(environment);
+                                                       ExecutableElement dbValueToObject,
+                                                       boolean external) {
+    final TransformerElement transformer = new TransformerElement(environment, external);
     transformer.addDbValueToObjectMethod(dbValueToObject);
     return transformer;
   }
diff --git a/compiler-core/src/main/java/com/siimkinks/sqlitemagic/processing/TransformerCollectionStep.java b/compiler-core/src/main/java/com/siimkinks/sqlitemagic/processing/TransformerCollectionStep.java
index 39b8c56..0004cce 100644
--- a/compiler-core/src/main/java/com/siimkinks/sqlitemagic/processing/TransformerCollectionStep.java
+++ b/compiler-core/src/main/java/com/siimkinks/sqlitemagic/processing/TransformerCollectionStep.java
@@ -2,12 +2,19 @@
 
 import com.siimkinks.sqlitemagic.BaseProcessor;
 import com.siimkinks.sqlitemagic.Environment;
+import com.siimkinks.sqlitemagic.annotation.Database;
+import com.siimkinks.sqlitemagic.annotation.SubmoduleDatabase;
 import com.siimkinks.sqlitemagic.annotation.transformer.DbValueToObject;
 import com.siimkinks.sqlitemagic.annotation.transformer.ObjectToDbValue;
 import com.siimkinks.sqlitemagic.element.TransformerElement;
+import com.siimkinks.sqlitemagic.util.ConditionCallback;
 import com.siimkinks.sqlitemagic.validator.TransformerValidator;
 
+import java.lang.annotation.Annotation;
+import java.util.ArrayList;
 import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
@@ -15,8 +22,13 @@
 import javax.inject.Inject;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.ExecutableElement;
+import javax.lang.model.element.Modifier;
 import javax.lang.model.element.TypeElement;
+import javax.lang.model.type.MirroredTypesException;
 import javax.lang.model.type.TypeMirror;
+import javax.lang.model.util.Elements;
+
+import static java.util.Collections.emptyList;
 
 public class TransformerCollectionStep implements ProcessingStep {
 
@@ -34,31 +46,116 @@ public boolean process(Set<? extends TypeElement> annotations, RoundEnvironment
     boolean isSuccessfulProcessing = true;
     final Map<String, TransformerElement> transformers = new HashMap<>();
 
-    for (Element element : roundEnv.getElementsAnnotatedWith(ObjectToDbValue.class)) {
+    final Set<? extends Element> objectToDbValueElements = roundEnv.getElementsAnnotatedWith(ObjectToDbValue.class);
+    final Set<? extends Element> dbValueToObjectElements = roundEnv.getElementsAnnotatedWith(DbValueToObject.class);
+    collectTransformers(
+        objectToDbValueElements,
+        dbValueToObjectElements,
+        transformers,
+        false
+    );
+
+    final List<TypeElement> externalTransformers = getExternalTransformers(roundEnv);
+    final Set<ExecutableElement> methods = getAllStaticMethods(externalTransformers);
+    collectTransformers(
+        filterMethodsWithAnnotation(methods, ObjectToDbValue.class),
+        filterMethodsWithAnnotation(methods, DbValueToObject.class),
+        transformers,
+        true
+    );
+
+    for (TransformerElement transformer : transformers.values()) {
+      if (!validator.isTransformerValid(transformer)) {
+        isSuccessfulProcessing = false;
+      } else {
+        environment.addTransformerElement(transformer);
+      }
+    }
+    return isSuccessfulProcessing;
+  }
+
+  private void collectTransformers(
+      Set<? extends Element> objectToDbValueElements,
+      Set<? extends Element> dbValueToObjectElements,
+      Map<String, TransformerElement> transformers,
+      boolean external
+  ) {
+    for (Element element : objectToDbValueElements) {
       final ExecutableElement objectToDbValue = (ExecutableElement) element;
-      final TransformerElement transformerElement = TransformerElement.fromObjectToDbValue(environment, objectToDbValue);
+      final TransformerElement transformerElement = TransformerElement.fromObjectToDbValue(environment, objectToDbValue, external);
       transformers.put(transformerElement.getRawDeserializedType().toString(), transformerElement);
     }
 
-    for (Element element : roundEnv.getElementsAnnotatedWith(DbValueToObject.class)) {
+    for (Element element : dbValueToObjectElements) {
       final ExecutableElement dbValueToObject = (ExecutableElement) element;
       final TypeMirror rawDeserializedType = dbValueToObject.getReturnType();
       final TransformerElement transformer = transformers.get(rawDeserializedType.toString());
       if (transformer != null) {
         transformer.addDbValueToObjectMethod(dbValueToObject);
       } else {
-        final TransformerElement incompleteTransformer = TransformerElement.fromDbValueToObject(environment, dbValueToObject);
+        final TransformerElement incompleteTransformer = TransformerElement.fromDbValueToObject(environment, dbValueToObject, external);
         transformers.put(incompleteTransformer.getRawDeserializedType().toString(), incompleteTransformer);
       }
     }
+  }
 
-    for (TransformerElement transformer : transformers.values()) {
-      if (!validator.isTransformerValid(transformer)) {
-        isSuccessfulProcessing = false;
+  private List<TypeElement> getExternalTransformers(RoundEnvironment roundEnv) {
+    final Elements elementUtils = environment.getElementUtils();
+    final List<TypeElement> result = new ArrayList<>();
+    final Class<?>[] externalTransformers;
+    try {
+      if (environment.isSubmodule()) {
+        final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(SubmoduleDatabase.class);
+        if (elements.isEmpty()) {
+          return emptyList();
+        }
+        final Element element = elements.iterator().next();
+        final SubmoduleDatabase annotation = element.getAnnotation(SubmoduleDatabase.class);
+        externalTransformers = annotation.externalTransformers();
       } else {
-        environment.addTransformerElement(transformer);
+        final Set<? extends Element> elements = roundEnv.getElementsAnnotatedWith(Database.class);
+        if (elements.isEmpty()) {
+          return emptyList();
+        }
+        final Element element = elements.iterator().next();
+        final Database annotation = element.getAnnotation(Database.class);
+        externalTransformers = annotation.externalTransformers();
       }
+    } catch (MirroredTypesException e) {
+      for (TypeMirror typeMirror : e.getTypeMirrors()) {
+        final TypeElement typeElement = elementUtils.getTypeElement(typeMirror.toString());
+        result.add(typeElement);
+      }
+      return result;
     }
-    return isSuccessfulProcessing;
+    for (Class<?> clazz : externalTransformers) {
+      final TypeElement typeElement = environment.getTypeElement(clazz);
+      result.add(typeElement);
+    }
+    return result;
+  }
+
+  private Set<ExecutableElement> getAllStaticMethods(List<TypeElement> externalTransformers) {
+    final HashSet<ExecutableElement> result = new HashSet<>();
+    for (TypeElement typeElement : externalTransformers) {
+      final Set<ExecutableElement> methods = environment.getLocalAndInheritedMethods(typeElement, new ConditionCallback<ExecutableElement>() {
+        @Override
+        public boolean call(ExecutableElement method) {
+          return method.getModifiers().contains(Modifier.STATIC);
+        }
+      });
+      result.addAll(methods);
+    }
+    return result;
+  }
+
+  private Set<ExecutableElement> filterMethodsWithAnnotation(Set<ExecutableElement> methods, Class<? extends Annotation> annotation) {
+    final HashSet<ExecutableElement> result = new HashSet<>();
+    for (ExecutableElement method : methods) {
+      if (method.getAnnotation(annotation) != null) {
+        result.add(method);
+      }
+    }
+    return result;
   }
 }
diff --git a/compiler-core/src/main/java/com/siimkinks/sqlitemagic/writer/TransformerWriter.java b/compiler-core/src/main/java/com/siimkinks/sqlitemagic/writer/TransformerWriter.java
index 979bc02..55e69b7 100644
--- a/compiler-core/src/main/java/com/siimkinks/sqlitemagic/writer/TransformerWriter.java
+++ b/compiler-core/src/main/java/com/siimkinks/sqlitemagic/writer/TransformerWriter.java
@@ -23,7 +23,7 @@ public void writeSource(Environment environment) throws IOException {
   private void writeTransformerColumns(Environment environment) throws IOException {
     final Filer filer = environment.getFiler();
     for (TransformerElement transformerElement : environment.getTransformerElements().values()) {
-      if (transformerElement.isDefaultTransformer()) {
+      if (transformerElement.isDefaultTransformer() || transformerElement.isExternal()) {
         continue;
       }
       ColumnClassWriter
diff --git a/sqlitemagic-tests/.gitignore b/sqlitemagic-tests/.gitignore
index ec193ba..d2191a2 100644
--- a/sqlitemagic-tests/.gitignore
+++ b/sqlitemagic-tests/.gitignore
@@ -6,4 +6,4 @@
 /captures
 **/db
 /db
-**/debug/assets/*.sql
\ No newline at end of file
+**/*debug/assets/*.sql
\ No newline at end of file
diff --git a/sqlitemagic-tests/another-submodule/build.gradle b/sqlitemagic-tests/another-submodule/build.gradle
index 9b367c6..5416c75 100644
--- a/sqlitemagic-tests/another-submodule/build.gradle
+++ b/sqlitemagic-tests/another-submodule/build.gradle
@@ -42,6 +42,8 @@ android {
 }
 
 dependencies {
+  implementation project(':submodule')
+
   implementation libraries.kotlinStdLib
   implementation libraries.rxJava2
   implementation libraries.supportSqliteFramework
diff --git a/sqlitemagic-tests/another-submodule/src/main/java/com/siimkinks/sqlitemagic/another/AnotherSubmoduleDatabaseConfig.kt b/sqlitemagic-tests/another-submodule/src/main/java/com/siimkinks/sqlitemagic/another/AnotherSubmoduleDatabaseConfig.kt
index 6d429ea..4989f30 100644
--- a/sqlitemagic-tests/another-submodule/src/main/java/com/siimkinks/sqlitemagic/another/AnotherSubmoduleDatabaseConfig.kt
+++ b/sqlitemagic-tests/another-submodule/src/main/java/com/siimkinks/sqlitemagic/another/AnotherSubmoduleDatabaseConfig.kt
@@ -1,6 +1,7 @@
 package com.siimkinks.sqlitemagic.another
 
 import com.siimkinks.sqlitemagic.annotation.SubmoduleDatabase
+import com.siimkinks.sqlitemagic.submodule.DbTransformers
 
-@SubmoduleDatabase("another")
+@SubmoduleDatabase("another", externalTransformers = [DbTransformers::class])
 interface AnotherSubmoduleDatabaseConfig
\ No newline at end of file
diff --git a/sqlitemagic-tests/another-submodule/src/main/java/com/siimkinks/sqlitemagic/another/ModelWithExternalTransformers.kt b/sqlitemagic-tests/another-submodule/src/main/java/com/siimkinks/sqlitemagic/another/ModelWithExternalTransformers.kt
new file mode 100644
index 0000000..5500db4
--- /dev/null
+++ b/sqlitemagic-tests/another-submodule/src/main/java/com/siimkinks/sqlitemagic/another/ModelWithExternalTransformers.kt
@@ -0,0 +1,11 @@
+package com.siimkinks.sqlitemagic.another
+
+import com.siimkinks.sqlitemagic.annotation.Id
+import com.siimkinks.sqlitemagic.annotation.Table
+import java.util.*
+
+@Table
+data class ModelWithExternalTransformers(
+    @Id val localId: Long?,
+    val date: Date
+)
\ No newline at end of file
diff --git a/sqlitemagic-tests/multimodule-app/src/test/java/com/siimkinks/sqlitemagic/multimodule/GenClassesManagerTest.kt b/sqlitemagic-tests/multimodule-app/src/test/java/com/siimkinks/sqlitemagic/multimodule/GenClassesManagerTest.kt
index fed5b38..266c2b3 100644
--- a/sqlitemagic-tests/multimodule-app/src/test/java/com/siimkinks/sqlitemagic/multimodule/GenClassesManagerTest.kt
+++ b/sqlitemagic-tests/multimodule-app/src/test/java/com/siimkinks/sqlitemagic/multimodule/GenClassesManagerTest.kt
@@ -18,7 +18,9 @@ class GenClassesManagerTest {
     assertThat(allChangedTables).isEqualTo(StringArraySet(arrayOf(
         "immutable_value_with_nullable_fields",
         "immutable_value",
-        "author"
+        "author",
+        "model_with_transformers",
+        "model_with_external_transformers"
     )))
   }
 
@@ -31,7 +33,7 @@ class GenClassesManagerTest {
   @Test
   fun tableCountIsAddedForAllTableCount() {
     assertThat(getNrOfTables(null))
-        .isEqualTo(3)
+        .isEqualTo(5)
   }
 
   @Test
@@ -43,7 +45,7 @@ class GenClassesManagerTest {
   @Test
   fun tableCountOfSubmodule() {
     assertThat(getNrOfTables("Submodule"))
-        .isEqualTo(2)
+        .isEqualTo(3)
   }
 
   @Test
diff --git a/sqlitemagic-tests/submodule/src/main/java/com/siimkinks/sqlitemagic/submodule/DbTransformers.kt b/sqlitemagic-tests/submodule/src/main/java/com/siimkinks/sqlitemagic/submodule/DbTransformers.kt
new file mode 100644
index 0000000..4e23223
--- /dev/null
+++ b/sqlitemagic-tests/submodule/src/main/java/com/siimkinks/sqlitemagic/submodule/DbTransformers.kt
@@ -0,0 +1,15 @@
+package com.siimkinks.sqlitemagic.submodule
+
+import com.siimkinks.sqlitemagic.annotation.transformer.DbValueToObject
+import com.siimkinks.sqlitemagic.annotation.transformer.ObjectToDbValue
+import java.util.*
+
+object DbTransformers {
+  @JvmStatic
+  @DbValueToObject
+  fun dbValueToDate(dbValue: Long?): Date? = dbValue?.let(::Date)
+
+  @JvmStatic
+  @ObjectToDbValue
+  fun dateToDbValue(date: Date?): Long? = date?.time
+}
\ No newline at end of file
diff --git a/sqlitemagic-tests/submodule/src/main/java/com/siimkinks/sqlitemagic/submodule/ModelWithTransformers.kt b/sqlitemagic-tests/submodule/src/main/java/com/siimkinks/sqlitemagic/submodule/ModelWithTransformers.kt
new file mode 100644
index 0000000..353b0ea
--- /dev/null
+++ b/sqlitemagic-tests/submodule/src/main/java/com/siimkinks/sqlitemagic/submodule/ModelWithTransformers.kt
@@ -0,0 +1,11 @@
+package com.siimkinks.sqlitemagic.submodule
+
+import com.siimkinks.sqlitemagic.annotation.Id
+import com.siimkinks.sqlitemagic.annotation.Table
+import java.util.*
+
+@Table
+data class ModelWithTransformers(
+    @Id val localId: Long?,
+    val date: Date
+)
\ No newline at end of file
diff --git a/sqlitemagic-tests/submodule/src/test/java/com/siimkinks/sqlitemagic/submodule/SubmoduleGenClassesManagerTest.kt b/sqlitemagic-tests/submodule/src/test/java/com/siimkinks/sqlitemagic/submodule/SubmoduleGenClassesManagerTest.kt
index 5d78be8..cad574f 100644
--- a/sqlitemagic-tests/submodule/src/test/java/com/siimkinks/sqlitemagic/submodule/SubmoduleGenClassesManagerTest.kt
+++ b/sqlitemagic-tests/submodule/src/test/java/com/siimkinks/sqlitemagic/submodule/SubmoduleGenClassesManagerTest.kt
@@ -12,25 +12,29 @@ class SubmoduleGenClassesManagerTest {
   fun clearDataReturnsAllModuleTables() {
     val allChangedTables = clearData(mock())
     assertThat(allChangedTables.size).isEqualTo(getNrOfTables(null))
-    assertThat(allChangedTables).isEqualTo(StringArraySet(arrayOf("immutable_value_with_nullable_fields", "immutable_value")))
+    assertThat(allChangedTables).isEqualTo(StringArraySet(arrayOf(
+        "immutable_value_with_nullable_fields",
+        "immutable_value",
+        "model_with_transformers"
+    )))
   }
 
   @Test
   fun tableCountIsNotChangedForAllTableCount() {
     assertThat(getNrOfTables(null))
-        .isEqualTo(2)
+        .isEqualTo(3)
   }
 
   @Test
   fun tableCountIsNotChangedForNativeModule() {
     assertThat(getNrOfTables(""))
-        .isEqualTo(2)
+        .isEqualTo(3)
   }
 
   @Test
   fun tableCountIsNotChangedForNativeModuleWithSubmoduleName() {
     assertThat(getNrOfTables("Submodule"))
-        .isEqualTo(2)
+        .isEqualTo(3)
   }
 
   @Test