diff --git a/dev-doc/updating-c-library.md b/dev-doc/updating-c-library.md
index 5a38a5698..a5e26af08 100644
--- a/dev-doc/updating-c-library.md
+++ b/dev-doc/updating-c-library.md
@@ -19,17 +19,17 @@ for the binding update script (see below) and
 for Flutter (`flutter_libs` and `sync_flutter_libs` plugins) on Linux and Windows:
 
 ```bash
-./tool/set-c-version.sh 4.2.0
+./tool/set-c-version.sh 4.3.0
 ```
 
 ```text
-* Update ObjectBox database for Flutter Linux/Windows, Dart Native apps to [4.2.0](https://github.com/objectbox/objectbox-c/releases/tag/v4.2.0).
+* Update ObjectBox database for Flutter Linux/Windows, Dart Native apps to [4.3.0](https://github.com/objectbox/objectbox-c/releases/tag/v4.3.0).
 ```
 
 ```text
-Update C library [4.1.0 -> 4.2.0]
+Update C library [4.2.0 -> 4.3.0]
 
-Includes database 4.2.0-2025-03-04
+Includes database 4.3.0-2025-05-12
 ```
 
 ### Android
@@ -37,19 +37,19 @@ Includes database 4.2.0-2025-03-04
 For the Flutter plugins on Android ([view releases](https://github.com/objectbox/objectbox-java/releases)):
 
 ```bash
-./tool/set-android-version.sh 4.2.0
+./tool/set-android-version.sh 4.3.0
 ```
 
 ```text
-* Update ObjectBox database for Flutter Android apps to 4.2.0.
+* Update ObjectBox database for Flutter Android apps to 4.3.0.
   If your project is [using Admin](https://docs.objectbox.io/data-browser#admin-for-android), make 
-  sure to update to `io.objectbox:objectbox-android-objectbrowser:4.2.0` in `android/app/build.gradle`.
+  sure to update to `io.objectbox:objectbox-android-objectbrowser:4.3.0` in `android/app/build.gradle`.
 ```
 
 ```text
-Update objectbox-android [4.1.0 -> 4.2.0]
+Update Android library [4.2.0 -> 4.3.0]
 
-Includes C API 4.2.0 and database 4.2.0-2025-03-04
+Includes C API 4.3.0 and database 4.3.0-2025-05-12
 ```
 
 Note: the embedded C API and ObjectBox version can be looked up
@@ -60,18 +60,18 @@ from the relevant objectbox repository release tag (like `java-4.1.0`).
 For the Flutter plugins on iOS/macOS ([view releases](https://github.com/objectbox/objectbox-swift/releases))
 
 ```bash
-./tool/set-swift-version.sh 4.2.0
+./tool/set-swift-version.sh 4.3.0
 ```
 
 ```text
-* Update ObjectBox database for Flutter iOS/macOS apps to 4.2.0.
+* Update ObjectBox database for Flutter iOS/macOS apps to 4.3.0.
   For existing projects, run `pod repo update` and `pod update ObjectBox` in the `ios` or `macos` directories.
 ```
 
 ```text
-Update ObjectBox Swift [4.1.0 -> 4.2.0]
+Update macOS/iOS library [4.2.0 -> 4.3.0]
 
-Includes C API 4.2.0 and database 4.2.0-2025-03-27
+Includes C API 4.3.0 and database 4.3.0-2025-05-12
 ```
 
 Note: the embedded C API and ObjectBox version can be looked up 
@@ -98,5 +98,5 @@ Then manually:
 - Commit as
 
 ```text
-Update C-API [4.1.0 -> 4.2.0]
+Update C-API [4.2.0 -> 4.3.0]
 ```
diff --git a/flutter_libs/android/build.gradle b/flutter_libs/android/build.gradle
index 788a1a9ad..2d885034f 100644
--- a/flutter_libs/android/build.gradle
+++ b/flutter_libs/android/build.gradle
@@ -52,6 +52,6 @@ android {
         // ObjectBox Android library that includes an ObjectBox C library version compatible with
         // the C API binding of the ObjectBox Dart package.
         // https://central.sonatype.com/search?q=g:io.objectbox%20objectbox-android
-        implementation "io.objectbox:objectbox-android:4.2.0"
+        implementation "io.objectbox:objectbox-android:4.3.0"
     }
 }
diff --git a/flutter_libs/ios/objectbox_flutter_libs.podspec b/flutter_libs/ios/objectbox_flutter_libs.podspec
index a26696e9d..da4ac3cd5 100644
--- a/flutter_libs/ios/objectbox_flutter_libs.podspec
+++ b/flutter_libs/ios/objectbox_flutter_libs.podspec
@@ -18,7 +18,7 @@ Pod::Spec.new do |s|
   s.source_files     = 'Classes/**/*'
 
   s.dependency 'Flutter'
-  s.dependency 'ObjectBox', '4.2.0'
+  s.dependency 'ObjectBox', '4.3.0'
 
   # Flutter.framework does not contain a i386 slice.
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
diff --git a/flutter_libs/linux/CMakeLists.txt b/flutter_libs/linux/CMakeLists.txt
index cbce9d6c1..9ddab841a 100644
--- a/flutter_libs/linux/CMakeLists.txt
+++ b/flutter_libs/linux/CMakeLists.txt
@@ -44,7 +44,7 @@ target_link_libraries(${PLUGIN_NAME} PRIVATE PkgConfig::GTK)
 # ----------------------------------------------------------------------
 # Download and add objectbox-c prebuilt library.
 
-set(OBJECTBOX_VERSION 4.2.0)
+set(OBJECTBOX_VERSION 4.3.0)
 
 set(OBJECTBOX_ARCH ${CMAKE_SYSTEM_PROCESSOR})
 if (${OBJECTBOX_ARCH} MATCHES "x86_64")
diff --git a/flutter_libs/macos/objectbox_flutter_libs.podspec b/flutter_libs/macos/objectbox_flutter_libs.podspec
index e6ef1d9af..3c95ce32f 100644
--- a/flutter_libs/macos/objectbox_flutter_libs.podspec
+++ b/flutter_libs/macos/objectbox_flutter_libs.podspec
@@ -18,7 +18,7 @@ Pod::Spec.new do |s|
   s.source_files     = 'Classes/**/*'
 
   s.dependency 'FlutterMacOS'
-  s.dependency 'ObjectBox', '4.2.0'
+  s.dependency 'ObjectBox', '4.3.0'
 
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }
   s.swift_version = '5.3'
diff --git a/flutter_libs/windows/CMakeLists.txt b/flutter_libs/windows/CMakeLists.txt
index eed019cbf..bb84e2398 100644
--- a/flutter_libs/windows/CMakeLists.txt
+++ b/flutter_libs/windows/CMakeLists.txt
@@ -50,7 +50,7 @@ set(objectbox_flutter_libs_bundled_libraries
 # ----------------------------------------------------------------------
 # Download and add objectbox-c prebuilt library.
 
-set(OBJECTBOX_VERSION 4.2.0)
+set(OBJECTBOX_VERSION 4.3.0)
 
 set(OBJECTBOX_ARCH ${CMAKE_SYSTEM_PROCESSOR})
 if (${OBJECTBOX_ARCH} MATCHES "AMD64")
diff --git a/install.sh b/install.sh
index bac35583d..261900e4c 100755
--- a/install.sh
+++ b/install.sh
@@ -5,7 +5,7 @@ set -eu
 # It's important that the generated dart bindings and the c-api library version match. Dart won't error on C function
 # signature mismatch, leading to obscure memory bugs.
 # For how to upgrade the version see dev-doc/updating-c-library.md
-cLibVersion=4.2.0
+cLibVersion=4.3.0
 os=$(uname)
 cLibArgs="$*"
 
diff --git a/objectbox/CHANGELOG.md b/objectbox/CHANGELOG.md
index 0454c0974..a619a1461 100644
--- a/objectbox/CHANGELOG.md
+++ b/objectbox/CHANGELOG.md
@@ -1,5 +1,14 @@
 ## latest
 
+* Update ObjectBox database for Flutter Linux/Windows, Dart Native apps to [4.3.0](https://github.com/objectbox/objectbox-c/releases/tag/v4.3.0).
+* Update ObjectBox database for Flutter Android apps to 4.3.0.
+  If your project is [using Admin](https://docs.objectbox.io/data-browser#admin-for-android), make
+  sure to update to `io.objectbox:objectbox-android-objectbrowser:4.3.0` in `android/app/build.gradle`.
+* Update ObjectBox database for Flutter iOS/macOS apps to 4.3.0.
+  For existing projects, run `pod repo update` and `pod update ObjectBox` in the `ios` or `macos` directories.
+* External property types (via [MongoDB connector](https://sync.objectbox.io/mongodb-sync-connector)):
+  add `jsonToNative` to support sub (embedded/nested) documents/arrays in MongoDB.
+
 ## 4.2.0 (2025-04-15)
 
 * Requires at least Dart SDK 3.4 or Flutter SDK 3.22.
diff --git a/objectbox/example/flutter/objectbox_demo_relations/android/app/build.gradle b/objectbox/example/flutter/objectbox_demo_relations/android/app/build.gradle
index 5da6c3569..1f108d141 100644
--- a/objectbox/example/flutter/objectbox_demo_relations/android/app/build.gradle
+++ b/objectbox/example/flutter/objectbox_demo_relations/android/app/build.gradle
@@ -83,5 +83,5 @@ dependencies {
     // Add the Android library with ObjectBox Admin only for debug builds.
     // Note: when the objectbox package updates, check if the Android
     // library below needs to be updated as well.
-    debugImplementation("io.objectbox:objectbox-android-objectbrowser:4.2.0")
+    debugImplementation("io.objectbox:objectbox-android-objectbrowser:4.3.0")
 }
diff --git a/objectbox/lib/src/annotations.dart b/objectbox/lib/src/annotations.dart
index fee4d5fa8..876fef2a5 100644
--- a/objectbox/lib/src/annotations.dart
+++ b/objectbox/lib/src/annotations.dart
@@ -593,6 +593,19 @@ enum ExternalPropertyType {
   /// Representing type: String
   javaScript,
 
+  /// A JSON string that is converted to a native representation in the external
+  /// system.
+  ///
+  /// For example, a JSON object on the ObjectBox side (string) would be
+  /// converted to an embedded document in MongoDB.
+  ///
+  /// It depends on the external system what kind of JSON structures is
+  /// supported. For MongoDB, this is very flexible and allows (nested) objects,
+  /// arrays, primitives, etc.
+  ///
+  /// Representing type: String
+  jsonToNative,
+
   /// A vector (array) of Int128 values.
   int128Vector,
 
diff --git a/objectbox/lib/src/modelinfo/enums.dart b/objectbox/lib/src/modelinfo/enums.dart
index d422dcebb..012972d1e 100644
--- a/objectbox/lib/src/modelinfo/enums.dart
+++ b/objectbox/lib/src/modelinfo/enums.dart
@@ -258,6 +258,8 @@ int externalTypeToOBXExternalType(ExternalPropertyType type) {
       return OBXExternalPropertyType.Bson;
     case ExternalPropertyType.javaScript:
       return OBXExternalPropertyType.JavaScript;
+    case ExternalPropertyType.jsonToNative:
+      return OBXExternalPropertyType.JsonToNative;
     case ExternalPropertyType.int128Vector:
       return OBXExternalPropertyType.Int128Vector;
     case ExternalPropertyType.uuidVector:
@@ -321,6 +323,13 @@ abstract class OBXExternalPropertyType {
   /// Representing type: String
   static const int JavaScript = 111;
 
+  /// A JSON string that is converted to a native representation in the external system.
+  /// For example, a JSON object on the ObjectBox side (string) would be converted to an embedded document in MongoDB.
+  /// It depends on the external system what kind of JSON structures is supported.
+  /// For MongoDB, this is very flexible and allows (nested) objects, arrays, primitives, etc.
+  /// Representing type: String
+  static const int JsonToNative = 112;
+
   /// A vector (array) of Int128 values
   static const int Int128Vector = 116;
 
diff --git a/objectbox/lib/src/native/bindings/bindings.dart b/objectbox/lib/src/native/bindings/bindings.dart
index 0a6d85924..40a8f600b 100644
--- a/objectbox/lib/src/native/bindings/bindings.dart
+++ b/objectbox/lib/src/native/bindings/bindings.dart
@@ -96,14 +96,14 @@ ObjectBoxC? _tryObjectBoxLibFile() {
 // libraries.
 // Library                 | C API | Database
 // ------------------------|-------|-----------------
-// objectbox-c             | 4.2.0 | 4.2.0-2025-03-04
-// ObjectBox Swift 4.2.0   | 4.2.0 | 4.2.0-2025-03-27
-// objectbox-android 4.2.0 | 4.2.0 | 4.2.0-2025-03-04
+// C library 4.3.0         | 4.3.0 | 4.3.0-2025-05-12
+// Android library 4.3.0   | 4.3.0 | 4.3.0-2025-05-12
+// macOS/iOS library 4.3.0 | 4.3.0 | 4.3.0-2025-05-12
 var _obxCminMajor = 4;
-var _obxCminMinor = 2;
+var _obxCminMinor = 3;
 var _obxCminPatch = 0;
 // Require minimum database version guaranteeing actual C API availability.
-var _obxDatabaseMinVersion = "4.2.0-2025-03-04";
+var _obxDatabaseMinVersion = "4.3.0-2025-05-12";
 
 bool _isSupportedVersion(ObjectBoxC obxc) {
   // Require a minimum C API version
diff --git a/objectbox/lib/src/native/bindings/objectbox-sync.h b/objectbox/lib/src/native/bindings/objectbox-sync.h
index 109bc8a3f..77da691a2 100644
--- a/objectbox/lib/src/native/bindings/objectbox-sync.h
+++ b/objectbox/lib/src/native/bindings/objectbox-sync.h
@@ -34,7 +34,7 @@
 #include "objectbox.h"
 
 #if defined(static_assert) || defined(__cplusplus)
-static_assert(OBX_VERSION_MAJOR == 4 && OBX_VERSION_MINOR == 2 && OBX_VERSION_PATCH == 0,  // NOLINT
+static_assert(OBX_VERSION_MAJOR == 4 && OBX_VERSION_MINOR == 3 && OBX_VERSION_PATCH == 0,  // NOLINT
               "Versions of objectbox.h and objectbox-sync.h files do not match, please update");
 #endif
 
diff --git a/objectbox/lib/src/native/bindings/objectbox.h b/objectbox/lib/src/native/bindings/objectbox.h
index 74ddf39a3..84376440e 100644
--- a/objectbox/lib/src/native/bindings/objectbox.h
+++ b/objectbox/lib/src/native/bindings/objectbox.h
@@ -52,7 +52,7 @@ extern "C" {
 /// When using ObjectBox as a dynamic library, you should verify that a compatible version was linked using
 /// obx_version() or obx_version_is_at_least().
 #define OBX_VERSION_MAJOR 4
-#define OBX_VERSION_MINOR 2
+#define OBX_VERSION_MINOR 3
 #define OBX_VERSION_PATCH 0  // values >= 100 are reserved for dev releases leading to the next minor/major increase
 
 //----------------------------------------------
@@ -669,7 +669,12 @@ typedef enum {
     /// JavaScript source code
     /// Representing type: String
     OBXExternalPropertyType_JavaScript = 111,
-    // OBXExternalPropertyType_Reserved5 = 112,
+    /// A JSON string that is converted to a native representation in the external system.
+    /// For example, a JSON object on the ObjectBox side (string) would be converted to an embedded document in MongoDB.
+    /// It depends on the external system what kind of JSON structures is supported.
+    /// For MongoDB, this is very flexible and allows (nested) objects, arrays, primitives, etc.
+    /// Representing type: String
+    OBXExternalPropertyType_JsonToNative = 112,
     // OBXExternalPropertyType_Reserved6 = 113,
     // OBXExternalPropertyType_Reserved7 = 114,
     // OBXExternalPropertyType_Reserved8 = 115,
diff --git a/objectbox/lib/src/native/bindings/objectbox_c.dart b/objectbox/lib/src/native/bindings/objectbox_c.dart
index 2e947f015..db1a845ec 100644
--- a/objectbox/lib/src/native/bindings/objectbox_c.dart
+++ b/objectbox/lib/src/native/bindings/objectbox_c.dart
@@ -10692,6 +10692,13 @@ abstract class OBXExternalPropertyType {
   /// Representing type: String
   static const int JavaScript = 111;
 
+  /// A JSON string that is converted to a native representation in the external system.
+  /// For example, a JSON object on the ObjectBox side (string) would be converted to an embedded document in MongoDB.
+  /// It depends on the external system what kind of JSON structures is supported.
+  /// For MongoDB, this is very flexible and allows (nested) objects, arrays, primitives, etc.
+  /// Representing type: String
+  static const int JsonToNative = 112;
+
   /// A vector (array) of Int128 values
   static const int Int128Vector = 116;
 
@@ -11669,7 +11676,7 @@ typedef obx_dart_closer
 
 const int OBX_VERSION_MAJOR = 4;
 
-const int OBX_VERSION_MINOR = 2;
+const int OBX_VERSION_MINOR = 3;
 
 const int OBX_VERSION_PATCH = 0;
 
diff --git a/objectbox_test/test/entity.dart b/objectbox_test/test/entity.dart
index 1bfcf3297..2fef9ee1a 100644
--- a/objectbox_test/test/entity.dart
+++ b/objectbox_test/test/entity.dart
@@ -476,6 +476,7 @@ class HnswObject {
 @ExternalName(name: 'my-mongo-entity')
 class EntityWithExternalType {
   @Id()
+  @ExternalType(type: ExternalPropertyType.uuid)
   int id = 0;
 
   @Property(type: PropertyType.byteVector)
@@ -490,6 +491,9 @@ class EntityWithExternalType {
   @ExternalName(name: 'my-mongo-rel')
   final mongoIdEntities = ToMany<EntityWithExternalType>();
 
+  @ExternalType(type: ExternalPropertyType.jsonToNative)
+  String? externalJsonToNative;
+
   EntityWithExternalType(this.mongoId, this.mongoUuid);
 }
 
diff --git a/objectbox_test/test/objectbox-model.json b/objectbox_test/test/objectbox-model.json
index ebb6adf65..cbde99aad 100644
--- a/objectbox_test/test/objectbox-model.json
+++ b/objectbox_test/test/objectbox-model.json
@@ -727,7 +727,7 @@
     },
     {
       "id": "16:5931645853908059165",
-      "lastPropertyId": "3:7670802129899081197",
+      "lastPropertyId": "4:6250975810854368520",
       "name": "EntityWithExternalType",
       "externalName": "my-mongo-entity",
       "properties": [
@@ -735,6 +735,7 @@
           "id": "1:3044824951282217899",
           "name": "id",
           "type": 6,
+          "externalType": 102,
           "flags": 1
         },
         {
@@ -749,6 +750,12 @@
           "type": 27,
           "externalType": 102,
           "externalName": "my-mongo-uuid"
+        },
+        {
+          "id": "4:6250975810854368520",
+          "name": "externalJsonToNative",
+          "type": 9,
+          "externalType": 112
         }
       ],
       "relations": [
diff --git a/sync_flutter_libs/android/build.gradle b/sync_flutter_libs/android/build.gradle
index 39ec10d25..4f3ff7d7f 100644
--- a/sync_flutter_libs/android/build.gradle
+++ b/sync_flutter_libs/android/build.gradle
@@ -52,6 +52,6 @@ android {
         // ObjectBox Android library that includes an ObjectBox C library version compatible with
         // the C API binding of the ObjectBox Dart package.
         // https://central.sonatype.com/search?q=g:io.objectbox%20objectbox-sync-android
-        implementation "io.objectbox:objectbox-sync-android:4.2.0"
+        implementation "io.objectbox:objectbox-sync-android:4.3.0"
     }
 }
diff --git a/sync_flutter_libs/ios/objectbox_sync_flutter_libs.podspec b/sync_flutter_libs/ios/objectbox_sync_flutter_libs.podspec
index 3267a9d1a..571176e00 100644
--- a/sync_flutter_libs/ios/objectbox_sync_flutter_libs.podspec
+++ b/sync_flutter_libs/ios/objectbox_sync_flutter_libs.podspec
@@ -18,7 +18,7 @@ Pod::Spec.new do |s|
   s.source_files     = 'Classes/**/*'
 
   s.dependency 'Flutter'
-  s.dependency 'ObjectBox', '4.2.0-sync'
+  s.dependency 'ObjectBox', '4.3.0-sync'
 
   # Flutter.framework does not contain a i386 slice.
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
diff --git a/sync_flutter_libs/linux/CMakeLists.txt b/sync_flutter_libs/linux/CMakeLists.txt
index 246d71b49..57757ae59 100644
--- a/sync_flutter_libs/linux/CMakeLists.txt
+++ b/sync_flutter_libs/linux/CMakeLists.txt
@@ -44,7 +44,7 @@ target_link_libraries(${PLUGIN_NAME} PRIVATE PkgConfig::GTK)
 # ----------------------------------------------------------------------
 # Download and add objectbox-c prebuilt library.
 
-set(OBJECTBOX_VERSION 4.2.0)
+set(OBJECTBOX_VERSION 4.3.0)
 
 set(OBJECTBOX_ARCH ${CMAKE_SYSTEM_PROCESSOR})
 if (${OBJECTBOX_ARCH} MATCHES "x86_64")
diff --git a/sync_flutter_libs/macos/objectbox_sync_flutter_libs.podspec b/sync_flutter_libs/macos/objectbox_sync_flutter_libs.podspec
index eab6f3d23..a0870a53a 100644
--- a/sync_flutter_libs/macos/objectbox_sync_flutter_libs.podspec
+++ b/sync_flutter_libs/macos/objectbox_sync_flutter_libs.podspec
@@ -14,7 +14,7 @@ Pod::Spec.new do |s|
   s.source_files     = 'Classes/**/*'
 
   s.dependency 'FlutterMacOS'
-  s.dependency 'ObjectBox', '4.2.0-sync'
+  s.dependency 'ObjectBox', '4.3.0-sync'
 
   s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES' }
   s.swift_version = '5.3'
diff --git a/sync_flutter_libs/windows/CMakeLists.txt b/sync_flutter_libs/windows/CMakeLists.txt
index 4fcd94c55..f8df47492 100644
--- a/sync_flutter_libs/windows/CMakeLists.txt
+++ b/sync_flutter_libs/windows/CMakeLists.txt
@@ -50,7 +50,7 @@ set(objectbox_sync_flutter_libs_bundled_libraries
 # ----------------------------------------------------------------------
 # Download and add objectbox-c prebuilt library.
 
-set(OBJECTBOX_VERSION 4.2.0)
+set(OBJECTBOX_VERSION 4.3.0)
 
 set(OBJECTBOX_ARCH ${CMAKE_SYSTEM_PROCESSOR})
 if (${OBJECTBOX_ARCH} MATCHES "AMD64")
diff --git a/tool/update-c-binding.sh b/tool/update-c-binding.sh
index 87789a244..5e49b37e3 100755
--- a/tool/update-c-binding.sh
+++ b/tool/update-c-binding.sh
@@ -5,7 +5,7 @@
 # copies the header files, makes some required modifications
 # and runs the ffigen binding generator on them.
 
-cLibVersion=4.2.0
+cLibVersion=4.3.0
 echo "Downloading C library source files from GitHub..."
 
 # Note: the release archives do not contain objectbox-dart.h, so get the full sources.