diff --git a/src/addons/userprofilefield/checkbox/checkbox.module.ts b/src/addons/userprofilefield/checkbox/checkbox.module.ts
index d6134503c..4b232c5e2 100644
--- a/src/addons/userprofilefield/checkbox/checkbox.module.ts
+++ b/src/addons/userprofilefield/checkbox/checkbox.module.ts
@@ -39,11 +39,9 @@ import { CoreComponentsModule } from '@components/components.module';
         {
             provide: APP_INITIALIZER,
             multi: true,
-            deps: [CoreUserProfileFieldDelegate, AddonUserProfileFieldCheckboxHandler],
-            useFactory: (
-                userProfileFieldDelegate: CoreUserProfileFieldDelegate,
-                handler: AddonUserProfileFieldCheckboxHandler,
-            ) => () => userProfileFieldDelegate.registerHandler(handler),
+            deps: [],
+            useFactory: () => () =>
+                CoreUserProfileFieldDelegate.instance.registerHandler(AddonUserProfileFieldCheckboxHandler.instance),
         },
     ],
     exports: [
diff --git a/src/addons/userprofilefield/checkbox/services/handlers/checkbox.ts b/src/addons/userprofilefield/checkbox/services/handlers/checkbox.ts
index 02d31fd4e..f085e2f3b 100644
--- a/src/addons/userprofilefield/checkbox/services/handlers/checkbox.ts
+++ b/src/addons/userprofilefield/checkbox/services/handlers/checkbox.ts
@@ -17,13 +17,14 @@ import { Injectable, Type } from '@angular/core';
 import { AuthEmailSignupProfileField } from '@features/login/services/login-helper';
 import { CoreUserProfileField } from '@features/user/services/user';
 import { CoreUserProfileFieldHandler, CoreUserProfileFieldHandlerData } from '@features/user/services/user-profile-field-delegate';
+import { makeSingleton } from '@singletons';
 import { AddonUserProfileFieldCheckboxComponent } from '../../component/checkbox';
 
 /**
  * Checkbox user profile field handlers.
  */
 @Injectable({ providedIn: 'root' })
-export class AddonUserProfileFieldCheckboxHandler implements CoreUserProfileFieldHandler {
+export class AddonUserProfileFieldCheckboxHandlerService implements CoreUserProfileFieldHandler {
 
     name = 'AddonUserProfileFieldCheckbox';
     type = 'checkbox';
@@ -74,3 +75,5 @@ export class AddonUserProfileFieldCheckboxHandler implements CoreUserProfileFiel
     }
 
 }
+
+export class AddonUserProfileFieldCheckboxHandler extends makeSingleton(AddonUserProfileFieldCheckboxHandlerService) {}
diff --git a/src/addons/userprofilefield/datetime/datetime.module.ts b/src/addons/userprofilefield/datetime/datetime.module.ts
index 02cd226f4..4d9625d8a 100644
--- a/src/addons/userprofilefield/datetime/datetime.module.ts
+++ b/src/addons/userprofilefield/datetime/datetime.module.ts
@@ -41,11 +41,9 @@ import { CorePipesModule } from '@pipes/pipes.module';
         {
             provide: APP_INITIALIZER,
             multi: true,
-            deps: [CoreUserProfileFieldDelegate, AddonUserProfileFieldDatetimeHandler],
-            useFactory: (
-                userProfileFieldDelegate: CoreUserProfileFieldDelegate,
-                handler: AddonUserProfileFieldDatetimeHandler,
-            ) => () => userProfileFieldDelegate.registerHandler(handler),
+            deps: [],
+            useFactory: () => () =>
+                CoreUserProfileFieldDelegate.instance.registerHandler(AddonUserProfileFieldDatetimeHandler.instance),
         },
     ],
     exports: [
diff --git a/src/addons/userprofilefield/datetime/services/handlers/datetime.ts b/src/addons/userprofilefield/datetime/services/handlers/datetime.ts
index b35feb867..5a1ab635f 100644
--- a/src/addons/userprofilefield/datetime/services/handlers/datetime.ts
+++ b/src/addons/userprofilefield/datetime/services/handlers/datetime.ts
@@ -18,13 +18,14 @@ import { AuthEmailSignupProfileField } from '@features/login/services/login-help
 import { CoreUserProfileField } from '@features/user/services/user';
 import { CoreUserProfileFieldHandler, CoreUserProfileFieldHandlerData } from '@features/user/services/user-profile-field-delegate';
 import { CoreTimeUtils } from '@services/utils/time';
+import { makeSingleton } from '@singletons';
 import { AddonUserProfileFieldDatetimeComponent } from '../../component/datetime';
 
 /**
  * Datetime user profile field handlers.
  */
 @Injectable({ providedIn: 'root' })
-export class AddonUserProfileFieldDatetimeHandler implements CoreUserProfileFieldHandler {
+export class AddonUserProfileFieldDatetimeHandlerService implements CoreUserProfileFieldHandler {
 
     name = 'AddonUserProfileFieldDatetime';
     type = 'datetime';
@@ -76,3 +77,5 @@ export class AddonUserProfileFieldDatetimeHandler implements CoreUserProfileFiel
     }
 
 }
+
+export class AddonUserProfileFieldDatetimeHandler extends makeSingleton(AddonUserProfileFieldDatetimeHandlerService) {}
diff --git a/src/addons/userprofilefield/menu/menu.module.ts b/src/addons/userprofilefield/menu/menu.module.ts
index e91183197..792d82624 100644
--- a/src/addons/userprofilefield/menu/menu.module.ts
+++ b/src/addons/userprofilefield/menu/menu.module.ts
@@ -41,11 +41,9 @@ import { CoreDirectivesModule } from '@directives/directives.module';
         {
             provide: APP_INITIALIZER,
             multi: true,
-            deps: [CoreUserProfileFieldDelegate, AddonUserProfileFieldMenuHandler],
-            useFactory: (
-                userProfileFieldDelegate: CoreUserProfileFieldDelegate,
-                handler: AddonUserProfileFieldMenuHandler,
-            ) => () => userProfileFieldDelegate.registerHandler(handler),
+            deps: [],
+            useFactory: () => () =>
+                CoreUserProfileFieldDelegate.instance.registerHandler(AddonUserProfileFieldMenuHandler.instance),
         },
     ],
     exports: [
diff --git a/src/addons/userprofilefield/menu/services/handlers/menu.ts b/src/addons/userprofilefield/menu/services/handlers/menu.ts
index d40444adf..7a9396aed 100644
--- a/src/addons/userprofilefield/menu/services/handlers/menu.ts
+++ b/src/addons/userprofilefield/menu/services/handlers/menu.ts
@@ -17,13 +17,14 @@ import { Injectable, Type } from '@angular/core';
 import { AuthEmailSignupProfileField } from '@features/login/services/login-helper';
 import { CoreUserProfileField } from '@features/user/services/user';
 import { CoreUserProfileFieldHandler, CoreUserProfileFieldHandlerData } from '@features/user/services/user-profile-field-delegate';
+import { makeSingleton } from '@singletons';
 import { AddonUserProfileFieldMenuComponent } from '../../component/menu';
 
 /**
  * Menu user profile field handlers.
  */
 @Injectable({ providedIn: 'root' })
-export class AddonUserProfileFieldMenuHandler implements CoreUserProfileFieldHandler {
+export class AddonUserProfileFieldMenuHandlerService implements CoreUserProfileFieldHandler {
 
     name = 'AddonUserProfileFieldMenu';
     type = 'menu';
@@ -74,3 +75,5 @@ export class AddonUserProfileFieldMenuHandler implements CoreUserProfileFieldHan
     }
 
 }
+
+export class AddonUserProfileFieldMenuHandler extends makeSingleton(AddonUserProfileFieldMenuHandlerService) {}
diff --git a/src/addons/userprofilefield/text/services/handlers/text.ts b/src/addons/userprofilefield/text/services/handlers/text.ts
index 11abe2c18..630872d5e 100644
--- a/src/addons/userprofilefield/text/services/handlers/text.ts
+++ b/src/addons/userprofilefield/text/services/handlers/text.ts
@@ -19,12 +19,13 @@ import { AddonUserProfileFieldTextComponent } from '../../component/text';
 import { CoreTextUtils } from '@services/utils/text';
 import { AuthEmailSignupProfileField } from '@features/login/services/login-helper';
 import { CoreUserProfileField } from '@features/user/services/user';
+import { makeSingleton } from '@singletons';
 
 /**
  * Text user profile field handlers.
  */
 @Injectable({ providedIn: 'root' })
-export class AddonUserProfileFieldTextHandler implements CoreUserProfileFieldHandler {
+export class AddonUserProfileFieldTextHandlerService implements CoreUserProfileFieldHandler {
 
     name = 'AddonUserProfileFieldText';
     type = 'text';
@@ -73,3 +74,5 @@ export class AddonUserProfileFieldTextHandler implements CoreUserProfileFieldHan
     }
 
 }
+
+export class AddonUserProfileFieldTextHandler extends makeSingleton(AddonUserProfileFieldTextHandlerService) {}
diff --git a/src/addons/userprofilefield/text/text.module.ts b/src/addons/userprofilefield/text/text.module.ts
index 7287868ae..edc4f1299 100644
--- a/src/addons/userprofilefield/text/text.module.ts
+++ b/src/addons/userprofilefield/text/text.module.ts
@@ -41,11 +41,9 @@ import { CoreDirectivesModule } from '@directives/directives.module';
         {
             provide: APP_INITIALIZER,
             multi: true,
-            deps: [CoreUserProfileFieldDelegate, AddonUserProfileFieldTextHandler],
-            useFactory: (
-                userProfileFieldDelegate: CoreUserProfileFieldDelegate,
-                handler: AddonUserProfileFieldTextHandler,
-            ) => () => userProfileFieldDelegate.registerHandler(handler),
+            deps: [],
+            useFactory: () => () =>
+                CoreUserProfileFieldDelegate.instance.registerHandler(AddonUserProfileFieldTextHandler.instance),
         },
     ],
     exports: [
diff --git a/src/addons/userprofilefield/textarea/services/handlers/textarea.ts b/src/addons/userprofilefield/textarea/services/handlers/textarea.ts
index 56ed58bcd..e1a233652 100644
--- a/src/addons/userprofilefield/textarea/services/handlers/textarea.ts
+++ b/src/addons/userprofilefield/textarea/services/handlers/textarea.ts
@@ -19,12 +19,13 @@ import { AddonUserProfileFieldTextareaComponent } from '../../component/textarea
 import { CoreTextUtils } from '@services/utils/text';
 import { AuthEmailSignupProfileField } from '@features/login/services/login-helper';
 import { CoreUserProfileField } from '@features/user/services/user';
+import { makeSingleton } from '@singletons';
 
 /**
  * Textarea user profile field handlers.
  */
 @Injectable({ providedIn: 'root' })
-export class AddonUserProfileFieldTextareaHandler implements CoreUserProfileFieldHandler {
+export class AddonUserProfileFieldTextareaHandlerService implements CoreUserProfileFieldHandler {
 
     name = 'AddonUserProfileFieldTextarea';
     type = 'textarea';
@@ -83,3 +84,5 @@ export class AddonUserProfileFieldTextareaHandler implements CoreUserProfileFiel
     }
 
 }
+
+export class AddonUserProfileFieldTextareaHandler extends makeSingleton(AddonUserProfileFieldTextareaHandlerService) {}
diff --git a/src/addons/userprofilefield/textarea/textarea.module.ts b/src/addons/userprofilefield/textarea/textarea.module.ts
index d42d37ab1..e07ef0e71 100644
--- a/src/addons/userprofilefield/textarea/textarea.module.ts
+++ b/src/addons/userprofilefield/textarea/textarea.module.ts
@@ -43,11 +43,9 @@ import { CoreEditorComponentsModule } from '@features/editor/components/componen
         {
             provide: APP_INITIALIZER,
             multi: true,
-            deps: [CoreUserProfileFieldDelegate, AddonUserProfileFieldTextareaHandler],
-            useFactory: (
-                userProfileFieldDelegate: CoreUserProfileFieldDelegate,
-                handler: AddonUserProfileFieldTextareaHandler,
-            ) => () => userProfileFieldDelegate.registerHandler(handler),
+            deps: [],
+            useFactory: () => () =>
+                CoreUserProfileFieldDelegate.instance.registerHandler(AddonUserProfileFieldTextareaHandler.instance),
         },
     ],
     exports: [
diff --git a/src/core/features/login/pages/email-signup/email-signup.ts b/src/core/features/login/pages/email-signup/email-signup.ts
index 8935a09e3..ba3d36dae 100644
--- a/src/core/features/login/pages/email-signup/email-signup.ts
+++ b/src/core/features/login/pages/email-signup/email-signup.ts
@@ -83,7 +83,6 @@ export class CoreLoginEmailSignupPage implements OnInit {
         protected navCtrl: NavController,
         protected fb: FormBuilder,
         protected route: ActivatedRoute,
-        protected userProfileFieldDelegate: CoreUserProfileFieldDelegate,
     ) {
         // Create the ageVerificationForm.
         this.ageVerificationForm = this.fb.group({
@@ -191,7 +190,7 @@ export class CoreLoginEmailSignupPage implements OnInit {
             { siteUrl: this.siteUrl },
         );
 
-        if (this.userProfileFieldDelegate.hasRequiredUnsupportedField(this.settings.profilefields)) {
+        if (CoreUserProfileFieldDelegate.instance.hasRequiredUnsupportedField(this.settings.profilefields)) {
             this.allRequiredSupported = false;
 
             throw new Error(Translate.instance.instant('core.login.signuprequiredfieldnotsupported'));
@@ -302,7 +301,7 @@ export class CoreLoginEmailSignupPage implements OnInit {
 
         try {
             // Get the data for the custom profile fields.
-            params.customprofilefields = await this.userProfileFieldDelegate.getDataForFields(
+            params.customprofilefields = await CoreUserProfileFieldDelegate.instance.getDataForFields(
                 this.settings?.profilefields,
                 true,
                 'email',
diff --git a/src/core/features/user/components/user-profile-field/user-profile-field.ts b/src/core/features/user/components/user-profile-field/user-profile-field.ts
index 6bccb4b92..678f7b200 100644
--- a/src/core/features/user/components/user-profile-field/user-profile-field.ts
+++ b/src/core/features/user/components/user-profile-field/user-profile-field.ts
@@ -40,10 +40,6 @@ export class CoreUserProfileFieldComponent implements OnInit {
     componentClass?: Type<unknown>; // The class of the component to render.
     data: CoreUserProfileFieldComponentData = {}; // Data to pass to the component.
 
-    constructor(
-        protected userProfileFieldsDelegate: CoreUserProfileFieldDelegate,
-    ) { }
-
     /**
      * Component being initialized.
      */
@@ -52,7 +48,7 @@ export class CoreUserProfileFieldComponent implements OnInit {
             return;
         }
 
-        this.componentClass = await this.userProfileFieldsDelegate.getComponent(this.field, this.signup);
+        this.componentClass = await CoreUserProfileFieldDelegate.instance.getComponent(this.field, this.signup);
 
         this.data.field = this.field;
         this.data.edit = CoreUtils.instance.isTrueOrOne(this.edit);
diff --git a/src/core/features/user/pages/profile/profile.page.ts b/src/core/features/user/pages/profile/profile.page.ts
index 86f53ecfe..f4e29d3bb 100644
--- a/src/core/features/user/pages/profile/profile.page.ts
+++ b/src/core/features/user/pages/profile/profile.page.ts
@@ -31,7 +31,7 @@ import {
     CoreUserProvider,
 } from '@features/user/services/user';
 import { CoreUserHelper } from '@features/user/services/user-helper';
-import { CoreUserDelegate, CoreUserProfileHandlerData } from '@features/user/services/user-delegate';
+import { CoreUserDelegate, CoreUserDelegateService, CoreUserProfileHandlerData } from '@features/user/services/user-delegate';
 import { CoreFileUploaderHelper } from '@features/fileuploader/services/fileuploader-helper';
 import { CoreIonLoadingElement } from '@classes/ion-loading';
 import { CoreUtils } from '@services/utils/utils';
@@ -64,7 +64,6 @@ export class CoreUserProfilePage implements OnInit, OnDestroy {
     constructor(
         protected route: ActivatedRoute,
         protected navCtrl: NavController,
-        protected userDelegate: CoreUserDelegate,
     ) {
 
         this.obsProfileRefreshed = CoreEvents.on<CoreUserProfileRefreshedData>(CoreUserProvider.PROFILE_REFRESHED, (data) => {
@@ -127,26 +126,26 @@ export class CoreUserProfilePage implements OnInit, OnDestroy {
             // If there's already a subscription, unsubscribe because we'll get a new one.
             this.subscription?.unsubscribe();
 
-            this.subscription = this.userDelegate.getProfileHandlersFor(user, this.courseId).subscribe((handlers) => {
+            this.subscription = CoreUserDelegate.instance.getProfileHandlersFor(user, this.courseId).subscribe((handlers) => {
                 this.actionHandlers = [];
                 this.newPageHandlers = [];
                 this.communicationHandlers = [];
                 handlers.forEach((handler) => {
                     switch (handler.type) {
-                        case CoreUserDelegate.TYPE_COMMUNICATION:
+                        case CoreUserDelegateService.TYPE_COMMUNICATION:
                             this.communicationHandlers.push(handler.data);
                             break;
-                        case CoreUserDelegate.TYPE_ACTION:
+                        case CoreUserDelegateService.TYPE_ACTION:
                             this.actionHandlers.push(handler.data);
                             break;
-                        case CoreUserDelegate.TYPE_NEW_PAGE:
+                        case CoreUserDelegateService.TYPE_NEW_PAGE:
                         default:
                             this.newPageHandlers.push(handler.data);
                             break;
                     }
                 });
 
-                this.isLoadingHandlers = !this.userDelegate.areHandlersLoaded(user.id);
+                this.isLoadingHandlers = !CoreUserDelegate.instance.areHandlersLoaded(user.id);
             });
 
             await this.checkUserImageUpdated();
diff --git a/src/core/features/user/services/db/user.ts b/src/core/features/user/services/database/user.ts
similarity index 100%
rename from src/core/features/user/services/db/user.ts
rename to src/core/features/user/services/database/user.ts
diff --git a/src/core/features/user/services/handlers/profile-link.ts b/src/core/features/user/services/handlers/profile-link.ts
index 4cd8b434b..e1453224d 100644
--- a/src/core/features/user/services/handlers/profile-link.ts
+++ b/src/core/features/user/services/handlers/profile-link.ts
@@ -18,12 +18,13 @@ import { Params } from '@angular/router';
 import { CoreContentLinksHandlerBase } from '@features/contentlinks/classes/base-handler';
 import { CoreContentLinksAction } from '@features/contentlinks/services/contentlinks-delegate';
 import { CoreContentLinksHelper } from '@features/contentlinks/services/contentlinks-helper';
+import { makeSingleton } from '@singletons';
 
 /**
  * Handler to treat links to user profiles.
  */
 @Injectable({ providedIn: 'root' })
-export class CoreUserProfileLinkHandler extends CoreContentLinksHandlerBase {
+export class CoreUserProfileLinkHandlerService extends CoreContentLinksHandlerBase {
 
     name = 'CoreUserProfileLinkHandler';
     // Match user/view.php and user/profile.php but NOT grade/report/user/.
@@ -74,3 +75,5 @@ export class CoreUserProfileLinkHandler extends CoreContentLinksHandlerBase {
     }
 
 }
+
+export class CoreUserProfileLinkHandler extends makeSingleton(CoreUserProfileLinkHandlerService) {}
diff --git a/src/core/features/user/services/handlers/profile-mail.ts b/src/core/features/user/services/handlers/profile-mail.ts
index 0b61adce8..a240fc59a 100644
--- a/src/core/features/user/services/handlers/profile-mail.ts
+++ b/src/core/features/user/services/handlers/profile-mail.ts
@@ -14,20 +14,21 @@
 
 import { Injectable } from '@angular/core';
 
-import { CoreUserDelegate, CoreUserProfileHandler, CoreUserProfileHandlerData } from '../user-delegate';
+import { CoreUserDelegateService, CoreUserProfileHandler, CoreUserProfileHandlerData } from '../user-delegate';
 import { CoreSites } from '@services/sites';
 import { CoreUtils } from '@services/utils/utils';
 import { CoreUserProfile } from '../user';
+import { makeSingleton } from '@singletons';
 
 /**
  * Handler to send a email to a user.
  */
 @Injectable({ providedIn: 'root' })
-export class CoreUserProfileMailHandler implements CoreUserProfileHandler {
+export class CoreUserProfileMailHandlerService implements CoreUserProfileHandler {
 
     name = 'CoreUserProfileMail';
     priority = 700;
-    type = CoreUserDelegate.TYPE_COMMUNICATION;
+    type = CoreUserDelegateService.TYPE_COMMUNICATION;
 
     /**
      * Check if handler is enabled.
@@ -73,3 +74,5 @@ export class CoreUserProfileMailHandler implements CoreUserProfileHandler {
     }
 
 }
+
+export class CoreUserProfileMailHandler extends makeSingleton(CoreUserProfileMailHandlerService) {}
diff --git a/src/core/features/user/services/handlers/sync-cron.ts b/src/core/features/user/services/handlers/sync-cron.ts
index 96a99cc17..b188d8d59 100644
--- a/src/core/features/user/services/handlers/sync-cron.ts
+++ b/src/core/features/user/services/handlers/sync-cron.ts
@@ -15,13 +15,14 @@
 import { Injectable } from '@angular/core';
 
 import { CoreCronHandler } from '@services/cron';
+import { makeSingleton } from '@singletons';
 import { CoreUserSync } from '../user-sync';
 
 /**
  * Synchronization cron handler.
  */
 @Injectable({ providedIn: 'root' })
-export class CoreUserSyncCronHandler implements CoreCronHandler {
+export class CoreUserSyncCronHandlerService implements CoreCronHandler {
 
     name = 'CoreUserSyncCronHandler';
 
@@ -48,3 +49,5 @@ export class CoreUserSyncCronHandler implements CoreCronHandler {
     }
 
 }
+
+export class CoreUserSyncCronHandler extends makeSingleton(CoreUserSyncCronHandlerService) {}
diff --git a/src/core/features/user/services/user-delegate.ts b/src/core/features/user/services/user-delegate.ts
index 0c11f480c..08b3f799f 100644
--- a/src/core/features/user/services/user-delegate.ts
+++ b/src/core/features/user/services/user-delegate.ts
@@ -19,6 +19,7 @@ import { CoreDelegate, CoreDelegateHandler } from '@classes/delegate';
 import { CoreUtils } from '@services/utils/utils';
 import { CoreEvents } from '@singletons/events';
 import { CoreUserProfile } from './user';
+import { makeSingleton } from '@singletons';
 
 /**
  * Interface that all user profile handlers must implement.
@@ -127,10 +128,8 @@ export interface CoreUserProfileHandlerToDisplay {
  * Service to interact with plugins to be shown in user profile. Provides functions to register a plugin
  * and notify an update in the data.
  */
-@Injectable({
-    providedIn: 'root',
-})
-export class CoreUserDelegate extends CoreDelegate<CoreUserProfileHandler> {
+@Injectable({ providedIn: 'root' })
+export class CoreUserDelegateService extends CoreDelegate<CoreUserProfileHandler> {
 
     /**
      * User profile handler type for communication.
@@ -164,7 +163,7 @@ export class CoreUserDelegate extends CoreDelegate<CoreUserProfileHandler> {
     constructor() {
         super('CoreUserDelegate', true);
 
-        CoreEvents.on<CoreUserUpdateHandlerData>(CoreUserDelegate.UPDATE_HANDLER_EVENT, (data) => {
+        CoreEvents.on<CoreUserUpdateHandlerData>(CoreUserDelegateService.UPDATE_HANDLER_EVENT, (data) => {
             if (!data || !data.handler || !this.userHandlers[data.userId]) {
                 return;
             }
@@ -255,7 +254,7 @@ export class CoreUserDelegate extends CoreDelegate<CoreUserProfileHandler> {
                         name: name,
                         data: handler.getDisplayData(user, courseId),
                         priority: handler.priority || 0,
-                        type: handler.type || CoreUserDelegate.TYPE_NEW_PAGE,
+                        type: handler.type || CoreUserDelegateService.TYPE_NEW_PAGE,
                     });
                 }
             } catch {
@@ -271,6 +270,8 @@ export class CoreUserDelegate extends CoreDelegate<CoreUserProfileHandler> {
 
 }
 
+export class CoreUserDelegate extends makeSingleton(CoreUserDelegateService) {}
+
 /**
  * Data passed to UPDATE_HANDLER_EVENT event.
  */
diff --git a/src/core/features/user/services/user-helper.ts b/src/core/features/user/services/user-helper.ts
index ffd636c6b..3b6bf0a39 100644
--- a/src/core/features/user/services/user-helper.ts
+++ b/src/core/features/user/services/user-helper.ts
@@ -20,9 +20,7 @@ import { CoreUserRole } from './user';
 /**
  * Service that provides some features regarding users information.
  */
-@Injectable({
-    providedIn: 'root',
-})
+@Injectable({ providedIn: 'root' })
 export class CoreUserHelperProvider {
 
     /**
diff --git a/src/core/features/user/services/user-offline.ts b/src/core/features/user/services/user-offline.ts
index 5afd27b7c..ebe3c8e3e 100644
--- a/src/core/features/user/services/user-offline.ts
+++ b/src/core/features/user/services/user-offline.ts
@@ -16,14 +16,12 @@ import { Injectable } from '@angular/core';
 
 import { CoreSites } from '@services/sites';
 import { makeSingleton } from '@singletons';
-import { PREFERENCES_TABLE_NAME, CoreUserPreferenceDBRecord } from './db/user';
+import { PREFERENCES_TABLE_NAME, CoreUserPreferenceDBRecord } from './database/user';
 
 /**
  * Service to handle offline user preferences.
  */
-@Injectable({
-    providedIn: 'root',
-})
+@Injectable({ providedIn: 'root' })
 export class CoreUserOfflineProvider {
 
     /**
diff --git a/src/core/features/user/services/user-profile-field-delegate.ts b/src/core/features/user/services/user-profile-field-delegate.ts
index 3f1ec6436..833686c4f 100644
--- a/src/core/features/user/services/user-profile-field-delegate.ts
+++ b/src/core/features/user/services/user-profile-field-delegate.ts
@@ -17,6 +17,7 @@ import { Injectable, Type } from '@angular/core';
 import { CoreDelegate, CoreDelegateHandler } from '@classes/delegate';
 import { CoreError } from '@classes/errors/error';
 import { AuthEmailSignupProfileField } from '@features/login/services/login-helper';
+import { makeSingleton } from '@singletons';
 import { CoreUserProfileField } from './user';
 
 /**
@@ -73,10 +74,8 @@ export interface CoreUserProfileFieldHandlerData {
 /**
  * Service to interact with user profile fields.
  */
-@Injectable({
-    providedIn: 'root',
-})
-export class CoreUserProfileFieldDelegate extends CoreDelegate<CoreUserProfileFieldHandler> {
+@Injectable({ providedIn: 'root' })
+export class CoreUserProfileFieldDelegateService extends CoreDelegate<CoreUserProfileFieldHandler> {
 
     protected handlerNameProperty = 'type';
 
@@ -206,3 +205,5 @@ export class CoreUserProfileFieldDelegate extends CoreDelegate<CoreUserProfileFi
     }
 
 }
+
+export class CoreUserProfileFieldDelegate extends makeSingleton(CoreUserProfileFieldDelegateService) {}
diff --git a/src/core/features/user/services/user.ts b/src/core/features/user/services/user.ts
index 2f1e074ab..f5055fa26 100644
--- a/src/core/features/user/services/user.ts
+++ b/src/core/features/user/services/user.ts
@@ -25,16 +25,14 @@ import { makeSingleton } from '@singletons';
 import { CoreEvents, CoreEventUserDeletedData } from '@singletons/events';
 import { CoreStatusWithWarningsWSResponse, CoreWSExternalWarning } from '@services/ws';
 import { CoreError } from '@classes/errors/error';
-import { USERS_TABLE_NAME, CoreUserDBRecord } from './db/user';
+import { USERS_TABLE_NAME, CoreUserDBRecord } from './database/user';
 
 const ROOT_CACHE_KEY = 'mmUser:';
 
 /**
  * Service to provide user functionalities.
  */
-@Injectable({
-    providedIn: 'root',
-})
+@Injectable({ providedIn: 'root' })
 export class CoreUserProvider {
 
     static readonly PARTICIPANTS_LIST_LIMIT = 50; // Max of participants to retrieve in each WS call.
diff --git a/src/core/features/user/user.module.ts b/src/core/features/user/user.module.ts
index 591ed616c..572a89da7 100644
--- a/src/core/features/user/user.module.ts
+++ b/src/core/features/user/user.module.ts
@@ -17,12 +17,14 @@ import { Routes } from '@angular/router';
 
 import { CoreMainMenuMoreRoutingModule } from '@features/mainmenu/pages/more/more-routing.module';
 import { CORE_SITE_SCHEMAS } from '@services/sites';
-import { SITE_SCHEMA, OFFLINE_SITE_SCHEMA } from './services/db/user';
+import { SITE_SCHEMA, OFFLINE_SITE_SCHEMA } from './services/database/user';
 import { CoreUserComponentsModule } from './components/components.module';
 import { CoreUserDelegate } from './services/user-delegate';
 import { CoreUserProfileMailHandler } from './services/handlers/profile-mail';
 import { CoreContentLinksDelegate } from '@features/contentlinks/services/contentlinks-delegate';
 import { CoreUserProfileLinkHandler } from './services/handlers/profile-link';
+import { CoreCronDelegate } from '@services/cron';
+import { CoreUserSyncCronHandler } from './services/handlers/sync-cron';
 
 const routes: Routes = [
     {
@@ -48,17 +50,11 @@ const routes: Routes = [
         {
             provide: APP_INITIALIZER,
             multi: true,
-            deps: [CoreUserDelegate, CoreUserProfileMailHandler, CoreContentLinksDelegate, CoreUserProfileLinkHandler],
-            useFactory: (
-                userDelegate: CoreUserDelegate,
-                mailHandler: CoreUserProfileMailHandler,
-                linksDelegate: CoreContentLinksDelegate,
-                profileLinkHandler: CoreUserProfileLinkHandler,
-
-            ) => () => {
-                // @todo: Register sync handler when init process has been fixed.
-                userDelegate.registerHandler(mailHandler);
-                linksDelegate.registerHandler(profileLinkHandler);
+            deps: [],
+            useFactory: () => () => {
+                CoreUserDelegate.instance.registerHandler(CoreUserProfileMailHandler.instance);
+                CoreContentLinksDelegate.instance.registerHandler(CoreUserProfileLinkHandler.instance);
+                CoreCronDelegate.instance.register(CoreUserSyncCronHandler.instance);
             },
         },
     ],