diff --git a/src/app/AppContainer.tsx b/src/app/AppContainer.tsx
index 16feec6df..03036d3e5 100644
--- a/src/app/AppContainer.tsx
+++ b/src/app/AppContainer.tsx
@@ -16,10 +16,13 @@ import Routing from './Routing';
 import styled from 'styled-components';
 import { useOnMount } from '../utils/customHooks';
 import VelgEnhet from './VelgEnhet';
-import usePersistentLogin from '../utils/hooks/use-persistent-login';
 import LoggetUtModal from './LoggetUtModal';
 import { useValgtenhet, ValgtEnhetProvider } from '../context/valgtenhet-state';
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
+import { usePersistentWWLogin } from '../login/use-persistent-ww-login';
+import usePersistentLogin from '../utils/hooks/use-persistent-login';
+import useFeatureToggle from '../components/featureToggle/useFeatureToggle';
+import { FeatureToggles } from '../components/featureToggle/toggleIDs';
 
 const AppStyle = styled.div`
     height: 100vh;
@@ -42,9 +45,16 @@ const ContentStyle = styled.div`
 const store = createStore(reducers, composeWithDevTools(applyMiddleware(thunk)));
 
 function App() {
-    const loginState = usePersistentLogin();
+    const loginStateOld = usePersistentLogin();
+    const loginStateNew = usePersistentWWLogin();
+    const { isOn: newLoginStateToggleIsOn } = useFeatureToggle(FeatureToggles.BrukWebworkerPaaInnLogging);
     const valgtEnhet = useValgtenhet().enhetId;
 
+    let loginState = loginStateOld;
+    if (newLoginStateToggleIsOn) {
+        loginState = loginStateNew;
+    }
+
     if (!valgtEnhet) {
         /**
          * valgt enhet hentes fra modiacontextholder, og mellomlagres i localStorage
diff --git a/src/components/featureToggle/toggleIDs.ts b/src/components/featureToggle/toggleIDs.ts
index c72d9f723..1e893c700 100644
--- a/src/components/featureToggle/toggleIDs.ts
+++ b/src/components/featureToggle/toggleIDs.ts
@@ -1,4 +1,5 @@
 export enum FeatureToggles {
     BrukSoknadsstatus = 'modiapersonoversikt.soknadsstatus-api',
+    BrukWebworkerPaaInnLogging = 'modiapersonoversikt.web-worker-paa-innlogging',
     DebugMeldingsFunksjonalitet = 'modiapersonoversikt.ny-send-melding-container'
 }
diff --git a/src/login/AcitivityMonitor.ts b/src/login/AcitivityMonitor.ts
new file mode 100644
index 000000000..46177cc67
--- /dev/null
+++ b/src/login/AcitivityMonitor.ts
@@ -0,0 +1,11 @@
+export class ActivityMonitor {
+    private lastActivity: number = new Date().getTime();
+
+    public update() {
+        this.lastActivity = new Date().getTime();
+    }
+
+    public timeSinceLastActivity(): number {
+        return new Date().getTime() - this.lastActivity;
+    }
+}
diff --git a/src/login/LoginStateManager.ts b/src/login/LoginStateManager.ts
new file mode 100644
index 000000000..da014a34d
--- /dev/null
+++ b/src/login/LoginStateManager.ts
@@ -0,0 +1,100 @@
+import { AuthIntropectionDTO } from '../utils/hooks/use-persistent-login';
+import { ActivityMonitor } from './AcitivityMonitor';
+import { INACTIVITY_LIMIT_IN_MS, PREEMPTIVE_REFRESH_TIME_IN_MS, RECALC_LOGIN_STATUS_INTERVAL_IN_MS } from './constants';
+import { timeToExpiration } from './timeToExpiration';
+
+export class LoginStateManager {
+    private timeout: ReturnType<typeof setTimeout> | null = null;
+    private interval: ReturnType<typeof setInterval> | null = null;
+    private activityMonitor = new ActivityMonitor();
+    private _refreshToken?: () => void;
+    private _onLoginStateUpdate?: (props: { isLoggedIn: boolean }) => void;
+
+    initialize = (refreshToken: () => void, onLoginStateUpdate: (props: { isLoggedIn: boolean }) => void) => {
+        this._refreshToken = refreshToken;
+        this._onLoginStateUpdate = onLoginStateUpdate;
+    };
+
+    private setupTokenRefresher = (timeToRefresh: number) => {
+        this.timeout = this.getTokenRefreshTimeout(this.activityMonitor, timeToRefresh);
+    };
+
+    private get refreshToken() {
+        if (!this._refreshToken) {
+            throw new Error('[LoginStateManager] var ikke initialisert med en metode for å refreshe token');
+        }
+        return this._refreshToken;
+    }
+
+    private get onLoginStateUpdate() {
+        if (!this._onLoginStateUpdate) {
+            throw new Error('[LoginStateManager] var ikke initialisert med en metode for å sende login oppdateringer');
+        }
+        return this._onLoginStateUpdate;
+    }
+
+    private getTokenRefreshTimeout = (activityMonitor: ActivityMonitor, timeToExpiration: number) => {
+        return setTimeout(() => {
+            if (activityMonitor.timeSinceLastActivity() < INACTIVITY_LIMIT_IN_MS) {
+                if (!this.refreshToken) {
+                    throw new Error('[LoginStateManager] Var ikke initialisert med ');
+                }
+                if (this.refreshToken) {
+                    this.refreshToken();
+                }
+            }
+        }, [timeToExpiration - PREEMPTIVE_REFRESH_TIME_IN_MS]);
+    };
+
+    private getLoginStateInterval = (auth: AuthIntropectionDTO) => {
+        return setInterval(() => {
+            const timeLeft = timeToExpiration(auth.expirationDate);
+            if (this.onLoginStateUpdate) {
+                this.onLoginStateUpdate({ isLoggedIn: timeLeft > 0 });
+            }
+        }, RECALC_LOGIN_STATUS_INTERVAL_IN_MS);
+    };
+
+    private onAuthStateUpdate = (auth: AuthIntropectionDTO) => {
+        this.stopTokenRefresher();
+        const timeToRefresh = timeToExpiration(auth.expirationDate);
+        if (timeToRefresh === 0) {
+            if (this.refreshToken) {
+                this.refreshToken();
+            }
+            return;
+        }
+        this.setupTokenRefresher(timeToRefresh);
+    };
+
+    private setupLoginStateNotifier = (auth: AuthIntropectionDTO) => {
+        this.stopLoginStateNotifier();
+        this.interval = this.getLoginStateInterval(auth);
+    };
+
+    private stopTokenRefresher = () => {
+        if (this.timeout) {
+            clearTimeout(this.timeout);
+        }
+    };
+
+    private stopLoginStateNotifier = () => {
+        if (this.interval) {
+            clearInterval(this.interval);
+        }
+    };
+
+    onUserActive = () => {
+        this.activityMonitor.update();
+    };
+
+    onUpdate = (auth: AuthIntropectionDTO) => {
+        this.onAuthStateUpdate(auth);
+        this.setupLoginStateNotifier(auth);
+    };
+
+    stopWork = () => {
+        this.stopTokenRefresher();
+        this.stopLoginStateNotifier();
+    };
+}
diff --git a/src/login/WebWorkerCommunicator.ts b/src/login/WebWorkerCommunicator.ts
new file mode 100644
index 000000000..a15aea252
--- /dev/null
+++ b/src/login/WebWorkerCommunicator.ts
@@ -0,0 +1,87 @@
+import { AuthIntropectionDTO } from '../utils/hooks/use-persistent-login';
+import { LoginStateManager } from './LoginStateManager';
+import { WWMessage, OutgoingMessageType, IncommingMessageType } from './types';
+
+export interface IWebWorkerCom {
+    initialize: (refreshToken: () => void, onLoginStateUpdate: (props: { isLoggedIn: boolean }) => void) => void;
+    onAuthChange: (newState: AuthIntropectionDTO) => void;
+    stop: () => void;
+    onUserActive: () => void;
+}
+
+export class WebWorkerCommunicator implements IWebWorkerCom {
+    private worker: Worker;
+    refreshToken?: () => void;
+    onLoginStateUpdate?: (props: { isLoggedIn: boolean }) => void;
+
+    constructor(worker: Worker) {
+        this.worker = worker;
+    }
+
+    initialize = (refreshToken: () => void, onLoginStateUpdate: (props: { isLoggedIn: boolean }) => void) => {
+        this.refreshToken = refreshToken;
+        this.onLoginStateUpdate = onLoginStateUpdate;
+        this.worker.onmessage = (message: MessageEvent<WWMessage<any>>) => {
+            const { type, payload } = message.data;
+            this.onMessage(type as OutgoingMessageType, payload);
+        };
+    };
+
+    private sendMessage = (type: IncommingMessageType, payload?: any) => {
+        const message: WWMessage<any> = {
+            type,
+            payload
+        };
+        this.worker.postMessage(message);
+    };
+
+    private onMessage = (type: OutgoingMessageType, payload?: any) => {
+        switch (type) {
+            case 'REFRESH_TOKEN': {
+                if (!this.refreshToken) {
+                    throw new Error('WebWorker was not initialized before being called');
+                }
+                console.log(new Date().valueOf(), 'Refresh token message');
+                this.refreshToken();
+                return;
+            }
+            case 'LOGIN_STATE_UPDATE': {
+                if (!this.onLoginStateUpdate) {
+                    throw new Error('WebWorker was not initialized before being called');
+                }
+                console.log(new Date().valueOf(), 'Login state update');
+                this.onLoginStateUpdate({ isLoggedIn: payload });
+                return;
+            }
+        }
+    };
+
+    onUserActive = () => {
+        this.sendMessage('USER_ACTIVE');
+    };
+
+    onAuthChange = (newState: AuthIntropectionDTO) => {
+        this.sendMessage('AUTH_STATE_UPDATE', newState);
+    };
+
+    stop = () => this.sendMessage('STOP_WORKER');
+}
+
+export class NoWorkerCommunicator implements IWebWorkerCom {
+    private loginStateManager = new LoginStateManager();
+
+    initialize = (refreshToken: () => void, onLoginStateUpdate: (props: { isLoggedIn: boolean }) => void) => {
+        this.loginStateManager.initialize(refreshToken, onLoginStateUpdate);
+    };
+
+    onAuthChange = (newState: AuthIntropectionDTO) => {
+        this.loginStateManager.onUpdate(newState);
+    };
+    stop = () => {
+        this.loginStateManager.stopWork();
+    };
+
+    onUserActive = () => {
+        this.loginStateManager.onUserActive();
+    };
+}
diff --git a/src/login/constants.ts b/src/login/constants.ts
new file mode 100644
index 000000000..6ec659ef5
--- /dev/null
+++ b/src/login/constants.ts
@@ -0,0 +1,8 @@
+export const SECOND_IN_MS = 1000;
+export const MINUTE_IN_MS = 60 * SECOND_IN_MS;
+
+export const RECALC_LOGIN_STATUS_INTERVAL_IN_MS = 30 * SECOND_IN_MS;
+export const INACTIVITY_LIMIT_IN_MS = 10 * MINUTE_IN_MS;
+export const PREEMPTIVE_REFRESH_TIME_IN_MS = 120 * SECOND_IN_MS;
+export const ESTIMATED_EXPIRATION_IN_MS = 3600 * SECOND_IN_MS;
+export const INVALID_EXPIRATION_DATE = -1;
diff --git a/src/login/persistentLoginWebWorkerFactory.ts b/src/login/persistentLoginWebWorkerFactory.ts
new file mode 100644
index 000000000..a550bce37
--- /dev/null
+++ b/src/login/persistentLoginWebWorkerFactory.ts
@@ -0,0 +1,16 @@
+import { IWebWorkerCom, NoWorkerCommunicator, WebWorkerCommunicator } from './WebWorkerCommunicator';
+
+export const persistentLoginWebworkerFactory = (): IWebWorkerCom => {
+    if (!Worker) {
+        console.warn('WebWorker er ikke støttet av nettleseren. Kjører innlogging logikk i hovedtråden.');
+        return new NoWorkerCommunicator();
+    }
+    let worker: Worker;
+    try {
+        worker = new Worker(new URL('../loginWebWorker', import.meta.url));
+        return new WebWorkerCommunicator(worker);
+    } catch (e) {
+        console.log(e);
+        return new NoWorkerCommunicator();
+    }
+};
diff --git a/src/login/timeToExpiration.ts b/src/login/timeToExpiration.ts
new file mode 100644
index 000000000..a8a8e3de9
--- /dev/null
+++ b/src/login/timeToExpiration.ts
@@ -0,0 +1,9 @@
+import { ESTIMATED_EXPIRATION_IN_MS, INVALID_EXPIRATION_DATE } from './constants';
+
+export const timeToExpiration = (expirationDate: number): number => {
+    if (expirationDate === INVALID_EXPIRATION_DATE) {
+        return ESTIMATED_EXPIRATION_IN_MS;
+    }
+    const currentDate = new Date().getTime();
+    return expirationDate - currentDate;
+};
diff --git a/src/login/types.ts b/src/login/types.ts
new file mode 100644
index 000000000..fcbf199f8
--- /dev/null
+++ b/src/login/types.ts
@@ -0,0 +1,6 @@
+export type OutgoingMessageType = 'LOGIN_STATE_UPDATE' | 'REFRESH_TOKEN';
+export type IncommingMessageType = 'AUTH_STATE_UPDATE' | 'STOP_WORKER' | 'USER_ACTIVE';
+export interface WWMessage<T> {
+    type: IncommingMessageType | OutgoingMessageType;
+    payload: T;
+}
diff --git a/src/login/use-persistent-ww-login.ts b/src/login/use-persistent-ww-login.ts
new file mode 100644
index 000000000..a57f0286f
--- /dev/null
+++ b/src/login/use-persistent-ww-login.ts
@@ -0,0 +1,74 @@
+import { useEffect, useMemo, useState } from 'react';
+import {
+    AuthIntropectionDTO,
+    ErrorReason,
+    INVALID_EXPIRATION_DATE,
+    PersistentLoginState
+} from '../utils/hooks/use-persistent-login';
+import { UseQueryResult, useQuery } from '@tanstack/react-query';
+import { FetchError, get } from '../api/api';
+import { apiBaseUri } from '../api/config';
+import { persistentLoginWebworkerFactory } from './persistentLoginWebWorkerFactory';
+
+const authResource = {
+    useFetch(): UseQueryResult<AuthIntropectionDTO, FetchError> {
+        return useQuery(['auth'], () => get(`${apiBaseUri}/tilgang/auth`));
+    }
+};
+
+const errorHandling = (auth: UseQueryResult<AuthIntropectionDTO, FetchError>): ErrorReason | undefined => {
+    if (auth.isError) {
+        return ErrorReason.FETCH_ERROR;
+    } else if (auth.data && auth.data.expirationDate === INVALID_EXPIRATION_DATE) {
+        return ErrorReason.INVALID_EXPIRATION_DATE;
+    }
+    return undefined;
+};
+
+const useAuthStateLogin = (auth: UseQueryResult<AuthIntropectionDTO, FetchError>) => {
+    const [isLoggedIn, setIsLoggedIn] = useState(true);
+    const [webWorkerCom] = useState(() => {
+        const worker = persistentLoginWebworkerFactory();
+        worker.initialize(auth.refetch, ({ isLoggedIn }) => setIsLoggedIn(isLoggedIn));
+        return worker;
+    });
+
+    useEffect(() => {
+        if (webWorkerCom) {
+            document.addEventListener('mousemove', webWorkerCom.onUserActive);
+            document.addEventListener('keydown', webWorkerCom.onUserActive);
+        }
+        return () => {
+            if (webWorkerCom) {
+                document.removeEventListener('mousemove', webWorkerCom.onUserActive);
+                document.removeEventListener('keydown', webWorkerCom.onUserActive);
+            }
+        };
+    }, [webWorkerCom]);
+
+    useEffect(() => {
+        if (auth.status === 'success') {
+            webWorkerCom.onAuthChange(auth.data);
+            return;
+        } else if (auth.status === 'error') {
+            setIsLoggedIn(false);
+            webWorkerCom.stop();
+        }
+    }, [auth, webWorkerCom]);
+
+    return isLoggedIn;
+};
+
+export const usePersistentWWLogin = (): PersistentLoginState => {
+    const auth = authResource.useFetch();
+    const errorStatus = errorHandling(auth);
+    const isLoggedIn = useAuthStateLogin(auth);
+
+    return useMemo(
+        () => ({
+            isLoggedIn,
+            errorStatus
+        }),
+        [isLoggedIn, errorStatus]
+    );
+};
diff --git a/src/loginWebWorker.ts b/src/loginWebWorker.ts
new file mode 100644
index 000000000..7b961c6a0
--- /dev/null
+++ b/src/loginWebWorker.ts
@@ -0,0 +1,43 @@
+/* eslint-disable no-restricted-globals */
+import { LoginStateManager } from './login/LoginStateManager';
+import { IncommingMessageType, OutgoingMessageType } from './login/types';
+
+const loginStateManager = new LoginStateManager();
+
+const register = () => {
+    console.log('Bruker webworker for å kontrollere inlogging');
+    self.addEventListener('message', handleEventMessage);
+};
+
+const handleEventMessage = (event: MessageEvent<{ type: IncommingMessageType; payload: any }>) => {
+    const { type, payload } = event.data;
+    switch (type) {
+        case 'STOP_WORKER':
+            loginStateManager.stopWork();
+            console.log('[loginWebWorker] Mottok melding: ', type);
+            return;
+        case 'AUTH_STATE_UPDATE':
+            loginStateManager.onUpdate(payload);
+            console.log(`[loginWebWorker] Mottok melding: ${type}, med: ${payload.expirationDate}`);
+            return;
+        case 'USER_ACTIVE':
+            loginStateManager.onUserActive();
+            return;
+    }
+};
+
+const sendRefreshMessage = () => {
+    sendMessage('REFRESH_TOKEN');
+};
+
+const sendIsLoggedIn = ({ isLoggedIn }: { isLoggedIn: boolean }) => {
+    sendMessage('LOGIN_STATE_UPDATE', isLoggedIn);
+};
+
+const sendMessage = <T>(type: OutgoingMessageType, payload?: T) => {
+    self.postMessage({ type, payload });
+};
+
+loginStateManager.initialize(sendRefreshMessage, sendIsLoggedIn);
+
+register();
diff --git a/src/setupTests.ts b/src/setupTests.ts
index ddf3d4ab8..aa399e934 100644
--- a/src/setupTests.ts
+++ b/src/setupTests.ts
@@ -7,6 +7,7 @@ import 'dayjs/locale/nb';
 import 'jest-enzyme';
 import 'jest-styled-components';
 import './extra-polyfills';
+import { IWebWorkerCom } from './login/WebWorkerCommunicator';
 dayjs.locale('nb');
 
 configure({ adapter: new EnzymeReactAdapter17() });
@@ -31,6 +32,8 @@ window.matchMedia = (query: string) => {
     return querylist as unknown as MediaQueryList;
 };
 
+global['Worker'] = undefined;
+
 // Mock react collapse sin UnmountClosed
 jest.mock('react-collapse', () => {
     return {
@@ -39,5 +42,20 @@ jest.mock('react-collapse', () => {
     };
 });
 
+/**
+ * Jest har ikke støtte for import.meta som må brukes for å kunne lage WebWorker med Webpack p.t.
+ * I framtiden burde man fjerne denne mocken når man skriver seg bort fra legacy pakker.
+ */
+
+const workerMock: IWebWorkerCom = {
+    initialize: () => null,
+    onAuthChange: () => null,
+    onUserActive: () => null,
+    stop: () => null
+};
+jest.mock('./login/persistentLoginWebWorkerFactory.ts', () => ({
+    persistentLoginWebworkerFactory: () => workerMock
+}));
+
 beforeEach(EnzymeContainer.beforeEachHandler);
 afterEach(EnzymeContainer.afterEachHandler);