diff --git a/apps/red-ui/src/app/app.module.ts b/apps/red-ui/src/app/app.module.ts
index add4c23ae..92a402ec1 100644
--- a/apps/red-ui/src/app/app.module.ts
+++ b/apps/red-ui/src/app/app.module.ts
@@ -98,6 +98,7 @@ import { HtmlDebugScreenComponent } from './screens/html-debug-screen/html-debug
 import { ReportDownloadBtnComponent } from './components/buttons/report-download-btn/report-download-btn.component';
 import { ProjectListingActionsComponent } from './screens/project-listing-screen/project-listing-actions/project-listing-actions.component';
 import { HasScrollbarDirective } from './utils/has-scrollbar.directive';
+import { PendingChangesGuard } from './utils/can-deactivate.guard';
 
 export function HttpLoaderFactory(httpClient: HttpClient) {
     return new TranslateHttpLoader(httpClient, '/assets/i18n/', '.json');
@@ -179,6 +180,7 @@ const routes = [
                         path: 'dictionaries/:type',
                         component: DictionaryOverviewScreenComponent,
                         canActivate: [CompositeRouteGuard],
+                        canDeactivate: [PendingChangesGuard],
                         data: {
                             routeGuards: [AuthGuard, RedRoleGuard, AppStateGuard]
                         }
@@ -195,6 +197,7 @@ const routes = [
                         path: 'rules',
                         component: RulesScreenComponent,
                         canActivate: [CompositeRouteGuard],
+                        canDeactivate: [PendingChangesGuard],
                         data: {
                             routeGuards: [AuthGuard, RedRoleGuard, AppStateGuard]
                         }
diff --git a/apps/red-ui/src/app/screens/admin/dictionary-overview-screen/dictionary-overview-screen.component.ts b/apps/red-ui/src/app/screens/admin/dictionary-overview-screen/dictionary-overview-screen.component.ts
index 5fb3163f9..42aec8f96 100644
--- a/apps/red-ui/src/app/screens/admin/dictionary-overview-screen/dictionary-overview-screen.component.ts
+++ b/apps/red-ui/src/app/screens/admin/dictionary-overview-screen/dictionary-overview-screen.component.ts
@@ -10,6 +10,7 @@ import { NotificationService, NotificationType } from '../../../notification/not
 import { TranslateService } from '@ngx-translate/core';
 import { Observable } from 'rxjs';
 import { saveAs } from 'file-saver';
+import { ComponentHasChanges } from '../../../utils/can-deactivate.guard';
 
 declare var ace;
 
@@ -18,7 +19,7 @@ declare var ace;
     templateUrl: './dictionary-overview-screen.component.html',
     styleUrls: ['./dictionary-overview-screen.component.scss']
 })
-export class DictionaryOverviewScreenComponent {
+export class DictionaryOverviewScreenComponent extends ComponentHasChanges {
     static readonly MIN_WORD_LENGTH: number = 2;
     public compareActive = false;
 
@@ -49,13 +50,14 @@ export class DictionaryOverviewScreenComponent {
     constructor(
         public readonly permissionsService: PermissionsService,
         private readonly _notificationService: NotificationService,
-        private readonly _translateService: TranslateService,
+        protected readonly _translateService: TranslateService,
         private readonly _dictionaryControllerService: DictionaryControllerService,
         private readonly _dialogService: DialogService,
         private readonly _router: Router,
         private readonly _activatedRoute: ActivatedRoute,
         private readonly _appStateService: AppStateService
     ) {
+        super(_translateService);
         this._activatedRoute.params.subscribe((params) => {
             this.dictionary = this._appStateService.dictionaryData[params.type];
             if (!this.dictionary) {
diff --git a/apps/red-ui/src/app/screens/admin/rules-screen/rules-screen.component.ts b/apps/red-ui/src/app/screens/admin/rules-screen/rules-screen.component.ts
index bb35a74f0..e1fef741a 100644
--- a/apps/red-ui/src/app/screens/admin/rules-screen/rules-screen.component.ts
+++ b/apps/red-ui/src/app/screens/admin/rules-screen/rules-screen.component.ts
@@ -5,6 +5,7 @@ import { RulesControllerService } from '@redaction/red-ui-http';
 import { NotificationService, NotificationType } from '../../../notification/notification.service';
 import { TranslateService } from '@ngx-translate/core';
 import { saveAs } from 'file-saver';
+import { ComponentHasChanges } from '../../../utils/can-deactivate.guard';
 
 declare var ace;
 
@@ -13,7 +14,7 @@ declare var ace;
     templateUrl: './rules-screen.component.html',
     styleUrls: ['./rules-screen.component.scss']
 })
-export class RulesScreenComponent {
+export class RulesScreenComponent extends ComponentHasChanges {
     public aceOptions = { showPrintMargin: false };
     public rules: string;
     public processing = true;
@@ -33,8 +34,9 @@ export class RulesScreenComponent {
         public readonly permissionsService: PermissionsService,
         private readonly _rulesControllerService: RulesControllerService,
         private readonly _notificationService: NotificationService,
-        private readonly _translateService: TranslateService
+        protected readonly _translateService: TranslateService
     ) {
+        super(_translateService);
         this._initialize();
     }
 
diff --git a/apps/red-ui/src/app/utils/can-deactivate.guard.ts b/apps/red-ui/src/app/utils/can-deactivate.guard.ts
new file mode 100644
index 000000000..001e23f87
--- /dev/null
+++ b/apps/red-ui/src/app/utils/can-deactivate.guard.ts
@@ -0,0 +1,38 @@
+import { CanDeactivate } from '@angular/router';
+import { Directive, HostListener, Injectable } from '@angular/core';
+import { Observable } from 'rxjs';
+import { TranslateService } from '@ngx-translate/core';
+
+export interface ComponentCanDeactivate {
+    hasChanges: boolean;
+}
+
+@Directive()
+export abstract class ComponentHasChanges implements ComponentCanDeactivate {
+    abstract hasChanges: boolean;
+
+    protected constructor(protected _translateService: TranslateService) {}
+
+    @HostListener('window:beforeunload', ['$event'])
+    unloadNotification($event: any) {
+        if (this.hasChanges) {
+            // This message will be displayed in IE/Edge
+            $event.returnValue = this._translateService.instant('pending-changes-guard');
+        }
+    }
+}
+
+@Injectable({ providedIn: 'root' })
+export class PendingChangesGuard implements CanDeactivate<ComponentCanDeactivate> {
+    constructor(private readonly translateService: TranslateService) {}
+
+    canDeactivate(component: ComponentCanDeactivate): boolean | Observable<boolean> {
+        // if there are no pending changes, just allow deactivation; else confirm first
+        return !component.hasChanges
+            ? true
+            : // NOTE: this warning message will only be shown when navigating elsewhere within your angular app;
+              // when navigating away from your angular app, the browser will show a generic warning message
+              // see http://stackoverflow.com/a/42207299/7307355
+              confirm(this.translateService.instant('pending-changes-guard'));
+    }
+}
diff --git a/apps/red-ui/src/assets/i18n/en.json b/apps/red-ui/src/assets/i18n/en.json
index 4c5e73292..4bef713fd 100644
--- a/apps/red-ui/src/assets/i18n/en.json
+++ b/apps/red-ui/src/assets/i18n/en.json
@@ -650,5 +650,6 @@
         "mark-unread": "Mark as unread"
     },
     "rule-editor": "Rule Editor",
-    "watermark": "Watermark"
+    "watermark": "Watermark",
+    "pending-changes-guard": "WARNING: You have unsaved changes. Press Cancel to go back and save these changes, or OK to lose these changes."
 }