diff --git a/client/lib/src/client.dart b/client/lib/src/client.dart
index b10cc3b..b3200c2 100644
--- a/client/lib/src/client.dart
+++ b/client/lib/src/client.dart
@@ -297,7 +297,12 @@ class MusicusClient {
     ));
 
     final json = jsonDecode(response.body);
-    return json.map<Person>((j) => Person.fromJson(j)).toList();
+    return json
+        .map<Person>((j) => Person.fromJson(j).copyWith(
+              sync: true,
+              synced: true,
+            ))
+        .toList();
   }
 
   /// Get a person by ID.
@@ -307,7 +312,10 @@ class MusicusClient {
     ));
 
     final json = jsonDecode(response.body);
-    return Person.fromJson(json);
+    return Person.fromJson(json).copyWith(
+      sync: true,
+      synced: true,
+    );
   }
 
   /// Delete a person by ID.
@@ -358,7 +366,12 @@ class MusicusClient {
     ));
 
     final json = jsonDecode(response.body);
-    return json.map<Instrument>((j) => Instrument.fromJson(j)).toList();
+    return json
+        .map<Instrument>((j) => Instrument.fromJson(j).copyWith(
+              sync: true,
+              synced: true,
+            ))
+        .toList();
   }
 
   /// Get an instrument by ID.
@@ -368,7 +381,10 @@ class MusicusClient {
     ));
 
     final json = jsonDecode(response.body);
-    return Instrument.fromJson(json);
+    return Instrument.fromJson(json).copyWith(
+      sync: true,
+      synced: true,
+    );
   }
 
   /// Create or update an instrument.
@@ -500,7 +516,12 @@ class MusicusClient {
     ));
 
     final json = jsonDecode(response.body);
-    return json.map<Ensemble>((j) => Ensemble.fromJson(j)).toList();
+    return json
+        .map<Ensemble>((j) => Ensemble.fromJson(j).copyWith(
+              sync: true,
+              synced: true,
+            ))
+        .toList();
   }
 
   /// Get an ensemble by ID.
@@ -510,7 +531,10 @@ class MusicusClient {
     ));
 
     final json = jsonDecode(response.body);
-    return Ensemble.fromJson(json);
+    return Ensemble.fromJson(json).copyWith(
+      sync: true,
+      synced: true,
+    );
   }
 
   /// Create or update an ensemble.
diff --git a/client/lib/src/database.dart b/client/lib/src/database.dart
index df74290..66e4058 100644
--- a/client/lib/src/database.dart
+++ b/client/lib/src/database.dart
@@ -45,6 +45,50 @@ class MusicusClientDatabase extends _$MusicusClientDatabase {
     this.client,
   }) : super.connect(connection);
 
+  /// Upload all changes to the server.
+  ///
+  /// If [update] is true, this will also update existing items with new data
+  /// from the server.
+  Future<void> sync([bool update = false]) async {
+    if (update) {
+      for (final person in await oldSyncPersons().get()) {
+        await updatePerson(await client.getPerson(person.id));
+      }
+      for (final instrument in await oldSyncInstruments().get()) {
+        await updateInstrument(await client.getInstrument(instrument.id));
+      }
+      for (final work in await oldSyncWorks().get()) {
+        final workInfo = await client.getWork(work.id);
+        await updateWork(workInfo);
+      }
+      for (final ensemble in await oldSyncEnsembles().get()) {
+        await updateEnsemble(await client.getEnsemble(ensemble.id));
+      }
+      for (final recording in await oldSyncRecordings().get()) {
+        final recordingInfo = await client.getRecording(recording.id);
+        await updateRecording(recordingInfo);
+      }
+    }
+
+    for (final person in await newSyncPersons().get()) {
+      await client.putPerson(person);
+    }
+    for (final instrument in await newSyncInstruments().get()) {
+      await client.putInstrument(instrument);
+    }
+    for (final work in await newSyncWorks().get()) {
+      final workInfo = await getWorkInfo(work);
+      await client.putWork(workInfo);
+    }
+    for (final ensemble in await newSyncEnsembles().get()) {
+      await client.putEnsemble(ensemble);
+    }
+    for (final recording in await newSyncRecordings().get()) {
+      final recordingInfo = await getRecordingInfo(recording);
+      await client.putRecording(recordingInfo);
+    }
+  }
+
   /// Get all available persons.
   ///
   /// This will return a list of [pageSize] persons. You can get another page
@@ -69,10 +113,14 @@ class MusicusClientDatabase extends _$MusicusClientDatabase {
       person,
       mode: InsertMode.insertOrReplace,
     );
+
+    if (person.sync) {
+      await sync();
+    }
   }
 
   /// Delete the person by [id].
-  /// 
+  ///
   /// If [sync] is true, the person will be deleted from the server too. If
   /// that fails, a MusicusNotAuthorizedException or MusicusNotLoggedInException
   /// willl be thrown and the person will NOT be deleted.
@@ -108,10 +156,14 @@ class MusicusClientDatabase extends _$MusicusClientDatabase {
       instrument,
       mode: InsertMode.insertOrReplace,
     );
+
+    if (instrument.sync) {
+      await sync();
+    }
   }
 
   /// Delete the instrument by [id].
-  /// 
+  ///
   /// If [sync] is true, the instrument will be deleted from the server too. If
   /// that fails, a MusicusNotAuthorizedException or MusicusNotLoggedInException
   /// willl be thrown and the instrument will NOT be deleted.
@@ -235,10 +287,14 @@ class MusicusClientDatabase extends _$MusicusClientDatabase {
         await into(workSections).insert(section);
       }
     });
+
+    if (workInfo.work.sync) {
+      await sync();
+    }
   }
 
   /// Delete the work by [id].
-  /// 
+  ///
   /// If [sync] is true, the work will be deleted from the server too. If
   /// that fails, a MusicusNotAuthorizedException or MusicusNotLoggedInException
   /// willl be thrown and the work will NOT be deleted.
@@ -276,10 +332,14 @@ class MusicusClientDatabase extends _$MusicusClientDatabase {
       ensemble,
       mode: InsertMode.insertOrReplace,
     );
+
+    if (ensemble.sync) {
+      await sync();
+    }
   }
 
   /// Delete the ensemble by [id].
-  /// 
+  ///
   /// If [sync] is true, the ensemble will be deleted from the server too. If
   /// that fails, a MusicusNotAuthorizedException or MusicusNotLoggedInException
   /// willl be thrown and the ensemble will NOT be deleted.
@@ -325,6 +385,10 @@ class MusicusClientDatabase extends _$MusicusClientDatabase {
         ));
       }
     });
+
+    if (recordingInfo.recording.sync) {
+      await sync();
+    }
   }
 
   /// Retreive more information on an already queried recording.
@@ -359,7 +423,7 @@ class MusicusClientDatabase extends _$MusicusClientDatabase {
   }
 
   /// Delete a recording by [id].
-  /// 
+  ///
   /// If [sync] is true, the recording will be deleted from the server too. If
   /// that fails, a MusicusNotAuthorizedException or MusicusNotLoggedInException
   /// willl be thrown and the recording will NOT be deleted.
diff --git a/client/lib/src/database.moor b/client/lib/src/database.moor
index 3544348..037006c 100644
--- a/client/lib/src/database.moor
+++ b/client/lib/src/database.moor
@@ -74,6 +74,12 @@ allPersons:
 SELECT * FROM persons ORDER BY last_name, first_name
     LIMIT :limit OFFSET :offset;
 
+newSyncPersons:
+SELECT * FROM persons WHERE sync = TRUE AND synced = FALSE;
+
+oldSyncPersons:
+SELECT * FROM persons WHERE sync = TRUE AND synced = TRUE;
+
 searchPersons:
 SELECT * FROM persons WHERE last_name LIKE :search
     ORDER BY last_name, first_name LIMIT :limit OFFSET :offset;
@@ -84,6 +90,12 @@ SELECT * FROM persons WHERE id = :id LIMIT 1;
 allInstruments:
 SELECT * FROM instruments ORDER BY name LIMIT :limit OFFSET :offset;
 
+newSyncInstruments:
+SELECT * FROM instruments WHERE sync = TRUE AND synced = FALSE;
+
+oldSyncInstruments:
+SELECT * FROM instruments WHERE sync = TRUE AND synced = TRUE;
+
 searchInstruments:
 SELECT * FROM instruments WHERE name LIKE :search ORDER BY name
     LIMIT :limit OFFSET :offset;
@@ -91,6 +103,12 @@ SELECT * FROM instruments WHERE name LIKE :search ORDER BY name
 instrumentById:
 SELECT * FROM instruments WHERE id = :id LIMIT 1;
 
+newSyncWorks:
+SELECT * FROM works WHERE sync = TRUE AND synced = FALSE;
+
+oldSyncWorks:
+SELECT * FROM works WHERE sync = TRUE AND synced = TRUE;
+
 workById:
 SELECT * FROM works WHERE id = :id LIMIT 1;
 
@@ -131,6 +149,12 @@ SELECT instruments.* FROM part_instrumentations
 allEnsembles:
 SELECT * FROM ensembles ORDER BY name LIMIT :limit OFFSET :offset;
 
+newSyncEnsembles:
+SELECT * FROM ensembles WHERE sync = TRUE AND synced = FALSE;
+
+oldSyncEnsembles:
+SELECT * FROM ensembles WHERE sync = TRUE AND synced = TRUE;
+
 searchEnsembles:
 SELECT * FROM ensembles WHERE name LIKE :search ORDER BY name
     LIMIT :limit OFFSET :offset;
@@ -138,6 +162,12 @@ SELECT * FROM ensembles WHERE name LIKE :search ORDER BY name
 ensembleById:
 SELECT * FROM ensembles WHERE id = :id LIMIT 1;
 
+newSyncRecordings:
+SELECT * FROM recordings WHERE sync = TRUE AND synced = FALSE;
+
+oldSyncRecordings:
+SELECT * FROM recordings WHERE sync = TRUE AND synced = TRUE;
+
 recordingById:
 SELECT * FROM recordings WHERE id = :id;