diff --git a/src/Squidex/app/features/settings/pages/contributors/contributors-page.component.ts b/src/Squidex/app/features/settings/pages/contributors/contributors-page.component.ts
index 4b2303a91..6e80b4379 100644
--- a/src/Squidex/app/features/settings/pages/contributors/contributors-page.component.ts
+++ b/src/Squidex/app/features/settings/pages/contributors/contributors-page.component.ts
@@ -15,6 +15,7 @@ import {
     AssignContributorForm,
     AutocompleteSource,
     ContributorsState,
+    Types,
     UserDto,
     UsersService
 } from '@app/shared';
@@ -85,7 +86,7 @@ export class ContributorsPageComponent implements OnInit {
         if (value) {
             let user = value.user;
 
-            if (user instanceof UserDto) {
+            if (Types.is(user, UserDto)) {
                 user = user.id;
             }
 
diff --git a/src/Squidex/app/framework/angular/forms/control-errors.component.ts b/src/Squidex/app/framework/angular/forms/control-errors.component.ts
index b14a04c73..c6c2cb653 100644
--- a/src/Squidex/app/framework/angular/forms/control-errors.component.ts
+++ b/src/Squidex/app/framework/angular/forms/control-errors.component.ts
@@ -9,7 +9,7 @@ import { ChangeDetectionStrategy, ChangeDetectorRef, Component, Host, Input, OnC
 import { AbstractControl, FormGroupDirective } from '@angular/forms';
 import { Observable, Subscription } from 'rxjs';
 
-import { fadeAnimation } from '@app/framework/internal';
+import { fadeAnimation, Types } from '@app/framework/internal';
 
 const DEFAULT_ERRORS: { [key: string]: string } = {
     required: '{field} is required.',
@@ -71,7 +71,7 @@ export class ControlErrorsComponent implements OnChanges, OnDestroy {
         if (this.fieldName) {
             this.displayFieldName = this.fieldName;
         } else if (this.for) {
-            if (typeof this.for === 'string') {
+            if (Types.isString(this.for)) {
                 this.displayFieldName = this.for.substr(0, 1).toUpperCase() + this.for.substr(1);
             } else {
                 this.displayFieldName = 'field';
@@ -80,7 +80,7 @@ export class ControlErrorsComponent implements OnChanges, OnDestroy {
 
         let control: AbstractControl | null = null;
 
-        if (typeof this.for === 'string') {
+        if (Types.isString(this.for)) {
             control = this.formGroupDirective.form.controls[this.for];
         } else {
             control = this.for;
diff --git a/src/Squidex/app/framework/angular/forms/copy.directive.ts b/src/Squidex/app/framework/angular/forms/copy.directive.ts
index 1f6d593b7..a46d78164 100644
--- a/src/Squidex/app/framework/angular/forms/copy.directive.ts
+++ b/src/Squidex/app/framework/angular/forms/copy.directive.ts
@@ -40,7 +40,7 @@ export class CopyDirective {
 
         element.focus();
 
-        if (element instanceof HTMLInputElement) {
+        if (Types.is(element, HTMLInputElement)) {
             element.setSelectionRange(0, element.value.length);
         }
 
@@ -56,7 +56,7 @@ export class CopyDirective {
             currentFocus.focus();
         }
 
-        if (element instanceof HTMLInputElement) {
+        if (Types.is(element, HTMLInputElement)) {
             element.setSelectionRange(prevSelectionStart!, prevSelectionEnd!);
         }
     }
diff --git a/src/Squidex/app/framework/angular/forms/validators.ts b/src/Squidex/app/framework/angular/forms/validators.ts
index 7fe3d8615..fabd1bbc9 100644
--- a/src/Squidex/app/framework/angular/forms/validators.ts
+++ b/src/Squidex/app/framework/angular/forms/validators.ts
@@ -18,7 +18,7 @@ export module ValidatorsEx {
         let regeExp: RegExp;
         let regexStr: string;
 
-        if (typeof regex === 'string') {
+        if (Types.isString(regex)) {
             regexStr = `^${regex}$`;
             regeExp = new RegExp(regexStr);
         } else {
diff --git a/src/Squidex/app/framework/angular/http/http-extensions-impl.ts b/src/Squidex/app/framework/angular/http/http-extensions-impl.ts
index 498776a54..8fad99a21 100644
--- a/src/Squidex/app/framework/angular/http/http-extensions-impl.ts
+++ b/src/Squidex/app/framework/angular/http/http-extensions-impl.ts
@@ -9,7 +9,7 @@ import { HttpClient, HttpErrorResponse, HttpHeaders, HttpResponse } from '@angul
 import { Observable } from 'rxjs';
 
 import { ErrorDto } from './../../utils/error';
-
+import { Types} from './../../utils/types';
 import { Version, Versioned } from './../../utils/version';
 
 export module HTTP {
@@ -64,9 +64,9 @@ export function pretifyError(message: string): Observable<any> {
     return this.catch((response: HttpErrorResponse) => {
         let result: ErrorDto | null = null;
 
-        if (!(response.error instanceof Error)) {
+        if (!Types.is(response.error, Error)) {
             try {
-                const errorDto = typeof response.error === 'object' ? response.error : JSON.parse(response.error);
+                const errorDto = Types.isObject(response.error) ? response.error : JSON.parse(response.error);
 
                 if (response.status === 412) {
                     result = new ErrorDto(response.status, 'Failed to make the update. Another user has made a change. Please reload.');
diff --git a/src/Squidex/app/framework/angular/modals/modal-view.directive.ts b/src/Squidex/app/framework/angular/modals/modal-view.directive.ts
index 636c6330e..895a8873f 100644
--- a/src/Squidex/app/framework/angular/modals/modal-view.directive.ts
+++ b/src/Squidex/app/framework/angular/modals/modal-view.directive.ts
@@ -8,7 +8,7 @@
 import { Directive, EmbeddedViewRef, Input, OnChanges, OnDestroy, Renderer2, SimpleChanges, TemplateRef, ViewContainerRef } from '@angular/core';
 import { Subscription } from 'rxjs';
 
-import { ModalView } from '@app/framework/internal';
+import { ModalView, Types } from '@app/framework/internal';
 
 import { RootViewComponent } from './root-view.component';
 
@@ -40,7 +40,7 @@ export class ModalViewDirective implements OnChanges, OnDestroy {
     public ngOnDestroy() {
         this.stopListening();
 
-        if (this.modalView instanceof ModalView) {
+        if (Types.is(this.modalView, ModalView)) {
             this.modalView.hide();
         }
     }
@@ -55,7 +55,7 @@ export class ModalViewDirective implements OnChanges, OnDestroy {
             this.subscription = null;
         }
 
-        if (this.modalView instanceof ModalView) {
+        if (Types.is(this.modalView, ModalView)) {
             this.subscription =
                 this.modalView.isOpen.subscribe(isOpen => {
                     this.update(isOpen);
diff --git a/src/Squidex/app/framework/services/analytics.service.ts b/src/Squidex/app/framework/services/analytics.service.ts
index b68937b2c..e6ba06235 100644
--- a/src/Squidex/app/framework/services/analytics.service.ts
+++ b/src/Squidex/app/framework/services/analytics.service.ts
@@ -9,6 +9,7 @@ import { Injectable } from '@angular/core';
 import { NavigationEnd, Router } from '@angular/router';
 
 import { AnalyticsIdConfig } from '../configurations';
+import { Types } from './../utils/types';
 import { ResourceLoaderService } from './resource-loader.service';
 
 // tslint:disable:only-arrow-functions
@@ -31,7 +32,7 @@ export class AnalyticsService {
         if (analyticsId && router && resourceLoader && window.location.hostname !== 'localhost') {
             this.gtag('config', analyticsId.value);
 
-            router.events.filter(e => e instanceof NavigationEnd)
+            router.events.filter(e => Types.is(e, NavigationEnd))
                 .subscribe(() => {
                     this.gtag('config', analyticsId.value, { page_path: window.location.pathname });
                 });
diff --git a/src/Squidex/app/framework/services/dialog.service.ts b/src/Squidex/app/framework/services/dialog.service.ts
index 72b9a0e00..b7d77d543 100644
--- a/src/Squidex/app/framework/services/dialog.service.ts
+++ b/src/Squidex/app/framework/services/dialog.service.ts
@@ -9,6 +9,7 @@ import { Injectable } from '@angular/core';
 import { Observable, Subject } from 'rxjs';
 
 import { ErrorDto } from './../utils/error';
+import { Types } from './../utils/types';
 
 export const DialogServiceFactory = () => {
     return new DialogService();
@@ -64,7 +65,7 @@ export class DialogService {
     }
 
     public notifyError(error: string | ErrorDto) {
-        if (error instanceof ErrorDto) {
+        if (Types.is(error, ErrorDto)) {
             this.notify(Notification.error(error.displayMessage));
         } else {
             this.notify(Notification.error(error));
diff --git a/src/Squidex/app/framework/state.ts b/src/Squidex/app/framework/state.ts
index 03bca305b..a53b4c1e4 100644
--- a/src/Squidex/app/framework/state.ts
+++ b/src/Squidex/app/framework/state.ts
@@ -9,6 +9,7 @@ import { AbstractControl } from '@angular/forms';
 import { BehaviorSubject, Observable } from 'rxjs';
 
 import { ErrorDto } from './utils/error';
+import { Types } from './utils/types';
 
 export interface FormState {
     submitted: boolean;
@@ -69,7 +70,7 @@ export class Form<T extends AbstractControl> {
     }
 
     private getError(error?: string | ErrorDto) {
-        if (error instanceof ErrorDto) {
+        if (Types.is(error, ErrorDto)) {
             return error.displayMessage;
         } else {
             return error;
@@ -100,7 +101,7 @@ export class State<T extends {}> {
     }
 
     public next(update: ((v: T) => T) | object) {
-        if (update instanceof Function) {
+        if (Types.isFunction(update)) {
             this.state.next(update(this.state.value));
         } else {
             this.state.next(Object.assign({}, this.snapshot, update));
diff --git a/src/Squidex/app/framework/utils/types.spec.ts b/src/Squidex/app/framework/utils/types.spec.ts
index 70fa846c8..f291b08c2 100644
--- a/src/Squidex/app/framework/utils/types.spec.ts
+++ b/src/Squidex/app/framework/utils/types.spec.ts
@@ -89,4 +89,17 @@ describe('Types', () => {
 
         expect(Types.isFunction([])).toBeFalsy();
     });
-});
\ No newline at end of file
+
+    it('should make type check', () => {
+        expect(Types.is(new MyClass(1), MyClass)).toBeTruthy();
+
+        expect(Types.is(1, MyClass)).toBeFalsy();
+    });
+});
+
+class MyClass {
+    constructor(
+        public readonly value: number
+    ) {
+    }
+}
\ No newline at end of file
diff --git a/src/Squidex/app/framework/utils/types.ts b/src/Squidex/app/framework/utils/types.ts
index d94c31a1c..437926303 100644
--- a/src/Squidex/app/framework/utils/types.ts
+++ b/src/Squidex/app/framework/utils/types.ts
@@ -46,6 +46,10 @@ export module Types {
         return value instanceof Date;
     }
 
+    export function is<TClass>(x: any, c: new (...args: any[]) => TClass): x is TClass {
+        return x instanceof c;
+    }
+
     export function isArrayOfNumber(value: any): value is Array<number> {
         return isArrayOf(value, v => isNumber(v));
     }
diff --git a/src/Squidex/app/shared/components/asset.component.ts b/src/Squidex/app/shared/components/asset.component.ts
index e9adb8739..919a56a30 100644
--- a/src/Squidex/app/shared/components/asset.component.ts
+++ b/src/Squidex/app/shared/components/asset.component.ts
@@ -18,6 +18,7 @@ import {
     fadeAnimation,
     ModalView,
     RenameAssetForm,
+    Types,
     UpdateAssetDto,
     Versioned
 } from '@app/shared/internal';
@@ -87,7 +88,7 @@ export class AssetComponent implements OnInit {
         if (initFile) {
             this.assetsService.uploadFile(this.appsState.appName, initFile, this.authState.user!.token, DateTime.now())
                 .subscribe(dto => {
-                    if (dto instanceof AssetDto) {
+                    if (Types.is(dto, AssetDto)) {
                         this.emitLoaded(dto);
                     } else {
                         this.progress = dto;
@@ -106,7 +107,7 @@ export class AssetComponent implements OnInit {
         if (files.length === 1) {
             this.assetsService.replaceFile(this.appsState.appName, this.asset.id, files[0], this.asset.version)
                 .subscribe(dto => {
-                    if (dto instanceof Versioned) {
+                    if (Types.is(dto, Versioned)) {
                         this.updateAsset(this.asset.update(dto.payload, this.authState.user!.token, dto.version), true);
                     } else {
                         this.setProgress(dto);
diff --git a/src/Squidex/app/shared/services/assets.service.ts b/src/Squidex/app/shared/services/assets.service.ts
index 5b2b9e147..7f58faa6b 100644
--- a/src/Squidex/app/shared/services/assets.service.ts
+++ b/src/Squidex/app/shared/services/assets.service.ts
@@ -14,6 +14,7 @@ import {
     ApiUrlConfig,
     DateTime,
     HTTP,
+    Types,
     Version,
     Versioned
 } from '@app/framework';
@@ -176,7 +177,7 @@ export class AssetsService {
                         const percentDone = event.total ? Math.round(100 * event.loaded / event.total) : 0;
 
                         return percentDone;
-                    } else if (event instanceof HttpResponse) {
+                    } else if (Types.is(event, HttpResponse)) {
                         const response: any = event.body;
                         const assetUrl = this.apiUrl.buildUrl(`api/assets/${response.id}`);
 
@@ -256,7 +257,7 @@ export class AssetsService {
                         const percentDone = event.total ? Math.round(100 * event.loaded / event.total) : 0;
 
                         return percentDone;
-                    } else if (event instanceof HttpResponse) {
+                    } else if (Types.is(event, HttpResponse)) {
                         const response: any = event.body;
 
                         const replaced =  new AssetReplacedDto(
diff --git a/src/Squidex/app/shared/services/auth.service.ts b/src/Squidex/app/shared/services/auth.service.ts
index b1f7ac20e..235c88461 100644
--- a/src/Squidex/app/shared/services/auth.service.ts
+++ b/src/Squidex/app/shared/services/auth.service.ts
@@ -15,7 +15,7 @@ import {
     WebStorageStateStore
 } from 'oidc-client';
 
-import { ApiUrlConfig } from '@app/framework';
+import { ApiUrlConfig, Types } from '@app/framework';
 
 export class Profile {
     public get id(): string {
@@ -163,7 +163,7 @@ export class AuthService {
 
         return observable.timeout(2000)
             .retryWhen(errors => errors
-                .mergeMap(e => e instanceof TimeoutError ? Observable.of(e) : Observable.throw(e))
+                .mergeMap(e => Types.is(e, TimeoutError) ? Observable.of(e) : Observable.throw(e))
                 .delay(500)
                 .take(5)
                 .concat(Observable.throw(new Error('Retry limit exceeded.'))));
diff --git a/src/Squidex/app/shared/state/schemas.state.ts b/src/Squidex/app/shared/state/schemas.state.ts
index 963f2d1a0..ec1a9ba9f 100644
--- a/src/Squidex/app/shared/state/schemas.state.ts
+++ b/src/Squidex/app/shared/state/schemas.state.ts
@@ -17,6 +17,7 @@ import {
     Form,
     ImmutableArray,
     State,
+    Types,
     ValidatorsEx,
     Version
 } from '@app/framework';
@@ -370,7 +371,7 @@ export class SchemasState extends State<Snapshot> {
 }
 
 const setPublished = (schema: SchemaDto | SchemaDetailsDto, publish: boolean, user: string, version: Version, now?: DateTime) => {
-    if (schema instanceof SchemaDetailsDto) {
+    if (Types.is(schema, SchemaDetailsDto)) {
         return new SchemaDetailsDto(
             schema.id,
             schema.name,