diff --git a/js/src/auth.js b/js/src/auth.js
new file mode 100644
index 0000000..905af34
--- /dev/null
+++ b/js/src/auth.js
@@ -0,0 +1,94 @@
+/*
+ * μlogger
+ *
+ * Copyright(C) 2019 Bartek Fabiszewski (www.fabiszewski.net)
+ *
+ * This is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+import uUser from './user.js';
+
+export default class uAuth {
+
+  constructor() {
+    /** @type {boolean} */
+    this._isAdmin = false;
+    /** @type {boolean} */
+    this._isAuthenticated = false;
+    /** @type {?uUser} */
+    this._user = null;
+  }
+
+  /**
+   * @param {uUser} user
+   */
+  set user(user) {
+    if (user) {
+      this._user = user;
+      this._isAuthenticated = true;
+    } else {
+      this._user = null;
+      this._isAuthenticated = false;
+      this._isAdmin = false;
+    }
+  }
+
+  /**
+   * @param {boolean} isAdmin
+   */
+  set isAdmin(isAdmin) {
+    if (!this._user) {
+      throw new Error('No authenticated user');
+    }
+    this._isAdmin = isAdmin;
+  }
+
+  /**
+   * @return {boolean}
+   */
+  get isAdmin() {
+    return this._isAdmin;
+  }
+
+  /**
+   * @return {boolean}
+   */
+  get isAuthenticated() {
+    return this._isAuthenticated;
+  }
+
+  /**
+   * @return {?uUser}
+   */
+  get user() {
+    return this._user;
+  }
+
+  /**
+   * Load auth state from data object
+   * @param {Object} data
+   * @param {boolean} data.isAdmin
+   * @param {boolean} data.isAuthenticated
+   * @param {?number} data.userId
+   * @param {?string} data.userLogin
+   */
+  load(data) {
+    if (data) {
+      if (data.isAuthenticated) {
+        this.user = new uUser(data.userId, data.userLogin);
+        this.isAdmin = data.isAdmin;
+      }
+    }
+  }
+}
diff --git a/js/test/auth.test.js b/js/test/auth.test.js
new file mode 100644
index 0000000..3fa4969
--- /dev/null
+++ b/js/test/auth.test.js
@@ -0,0 +1,142 @@
+/*
+ * μlogger
+ *
+ * Copyright(C) 2019 Bartek Fabiszewski (www.fabiszewski.net)
+ *
+ * This is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+import uAuth from '../src/auth.js';
+import uUser from '../src/user.js';
+
+describe('Auth tests', () => {
+
+  let auth;
+  let user;
+
+  beforeEach(() => {
+    auth = new uAuth();
+    user = new uUser(1, 'testUser');
+  });
+
+  it('should create instance', () => {
+    expect(auth.isAdmin).toBe(false);
+    expect(auth.isAuthenticated).toBe(false);
+    expect(auth.user).toBe(null);
+  });
+
+  it('should set authenticated user', () => {
+    // when
+    auth.user = user;
+    // then
+    expect(auth.user).toBe(user);
+    expect(auth.isAuthenticated).toBe(true);
+    expect(auth.isAdmin).toBe(false);
+  });
+
+  it('should unset authenticated user', () => {
+    // given
+    auth.user = user;
+    auth.isAdmin = true;
+    // when
+    auth.user = null;
+    // then
+    expect(auth.user).toBe(null);
+    expect(auth.isAuthenticated).toBe(false);
+    expect(auth.isAdmin).toBe(false);
+  });
+
+  it('should set user as admin', () => {
+    // given
+    auth.user = user;
+    // when
+    auth.isAdmin = true;
+    // then
+    expect(auth.user).toBe(user);
+    expect(auth.isAuthenticated).toBe(true);
+    expect(auth.isAdmin).toBe(true);
+  });
+
+  it('should throw error when setting admin when no user is defined', () => {
+    // given
+    auth.user = null;
+    // when
+    // then
+    expect(() => { auth.isAdmin = true; }).toThrowError('No authenticated user');
+    expect(auth.user).toBe(null);
+    expect(auth.isAuthenticated).toBe(false);
+    expect(auth.isAdmin).toBe(false);
+  });
+
+  it('should initialize with loaded data', () => {
+    // given
+    auth.user = null;
+    const data = {
+      isAdmin: false,
+      isAuthenticated: true,
+      userId: 5,
+      userLogin: 'dataUser'
+    };
+    // when
+    auth.load(data);
+    // then
+    expect(auth.user).toEqual(new uUser(data.userId, data.userLogin));
+    expect(auth.isAuthenticated).toBe(true);
+    expect(auth.isAdmin).toBe(false);
+  });
+
+  it('should initialize with loaded data containing admin user', () => {
+    // given
+    auth.user = null;
+    const data = {
+      isAdmin: true,
+      isAuthenticated: true,
+      userId: 5,
+      userLogin: 'dataUser'
+    };
+    // when
+    auth.load(data);
+    // then
+    expect(auth.user).toEqual(new uUser(data.userId, data.userLogin));
+    expect(auth.isAuthenticated).toBe(true);
+    expect(auth.isAdmin).toBe(true);
+  });
+
+  it('should skip loaded data if isAuthenticated is not set', () => {
+    // given
+    auth.user = null;
+    const data = {
+      userId: 5,
+      userLogin: 'dataUser'
+    };
+    // when
+    auth.load(data);
+    // then
+    expect(auth.user).toBe(null);
+    expect(auth.isAuthenticated).toBe(false);
+    expect(auth.isAdmin).toBe(false);
+  });
+
+  it('should skip loading if data is not set', () => {
+    // given
+    auth.user = null;
+    // when
+    auth.load(null);
+    // then
+    expect(auth.user).toBe(null);
+    expect(auth.isAuthenticated).toBe(false);
+    expect(auth.isAdmin).toBe(false);
+  });
+
+});