diff --git a/css/src/main.css b/css/src/main.css
index a7ce408..c5651a0 100644
--- a/css/src/main.css
+++ b/css/src/main.css
@@ -526,6 +526,43 @@ button > * {
   margin: 0 5px;
 }
 
+.alert {
+  position: fixed;
+  top: 0;
+  left: 50%;
+  width: 300px;
+  background: #666;
+  color: white;
+  font-family: "Open Sans", Verdana, sans-serif;
+  font-size: 0.8em;
+  line-height: 20px;
+  text-align: center;
+  -moz-osx-font-smoothing: grayscale;
+  -webkit-font-smoothing: antialiased;
+  margin: 1em 0 1em -150px;
+  padding: 6px 20px;
+  border-radius: 5px;
+  border-top: 1px solid #555;
+  box-shadow: 10px 10px 10px -8px rgba(0, 0, 0, 0.3);
+}
+
+.alert.error {
+  background: #d95b5b;
+  border-top: 1px solid #d05858;
+}
+
+.alert button {
+  position: absolute;
+  top: -1px;
+  right: 0;
+  border: none;
+  margin: 0;
+  height: 100%;
+  background: none;
+  font-weight: normal;
+  font-size: 15px;
+}
+
 /* chart */
 .ct-point {
   transition: 0.3s;
diff --git a/js/src/alert.js b/js/src/alert.js
new file mode 100644
index 0000000..4b661b9
--- /dev/null
+++ b/js/src/alert.js
@@ -0,0 +1,132 @@
+/*
+ * 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 uUtils from './utils.js';
+
+export default class uAlert {
+
+  /**
+   * @typedef {Object} AlertOptions
+   * @property {number} [autoClose=0] Optional autoclose delay time in ms, default 0 – no autoclose
+   * @property {string} [id] Optional box id
+   * @property {string} [class] Optional box class
+   */
+
+  /**
+   * Builds alert box
+   * @param {string} message
+   * @param {AlertOptions} [options] Optional options
+   */
+  constructor(message, options = {}) {
+    this.autoClose = options.autoClose || 0;
+    const html = `<div class="alert"><span>${message}</span></div>`;
+    this.box = uUtils.nodeFromHtml(html);
+    if (options.id) {
+      this.box.id = options.id;
+    }
+    if (options.class) {
+      this.box.classList.add(options.class);
+    }
+    if (this.autoClose === 0) {
+      const button = document.createElement('button');
+      button.setAttribute('type', 'button');
+      button.textContent = '×';
+      button.onclick = () => this.destroy();
+      this.box.appendChild(button);
+    }
+    this.closeHandle = null;
+  }
+
+  /**
+   * Calculate new box top offset
+   * @return {number} Top offset
+   */
+  static getPosition() {
+    const boxes = document.querySelectorAll('.alert');
+    const lastBox = boxes[boxes.length - 1];
+    let position = 0;
+    if (lastBox) {
+      const maxPosition = document.body.clientHeight - 100;
+      position = lastBox.getBoundingClientRect().bottom;
+      if (position > maxPosition) {
+        position = maxPosition;
+      }
+    }
+    return position;
+  }
+
+  render() {
+    const top = uAlert.getPosition();
+    if (top) {
+      this.box.style.top = `${top}px`;
+    }
+    document.body.appendChild(this.box);
+  }
+
+  destroy() {
+    if (this.closeHandle) {
+      clearTimeout(this.closeHandle);
+      this.closeHandle = null;
+    }
+    if (this.box) {
+      if (document.body.contains(this.box)) {
+        document.body.removeChild(this.box);
+      }
+      this.box = null;
+    }
+  }
+
+  /**
+   * Show alert box
+   * @param {string} message
+   * @param {AlertOptions} [options] Optional options
+   * @return uAlert
+   */
+  static show(message, options) {
+    const box = new uAlert(message, options);
+    box.render();
+    if (box.autoClose) {
+      box.closeHandle = setTimeout(() => box.destroy(), box.autoClose);
+    }
+    return box;
+  }
+
+  /**
+   * Show alert error box
+   * @param {string} message
+   * @param {Error=} e Optional error to be logged to console
+   * @return uAlert
+   */
+  static error(message, e) {
+    if (e instanceof Error) {
+      console.error(`${e.name}: ${e.message} (${e.stack})`);
+    }
+    return this.show(message, { class: 'error' });
+  }
+
+  /**
+   * Show alert toast box
+   * @param {string} message
+   * @return uAlert
+   */
+  static toast(message) {
+    return this.show(message, { class: 'toast', autoClose: 10000 });
+  }
+
+}
diff --git a/js/src/utils.js b/js/src/utils.js
index 303d8cd..7cf527a 100644
--- a/js/src/utils.js
+++ b/js/src/utils.js
@@ -280,22 +280,6 @@ export default class uUtils {
     window.location.assign(url);
   }
 
-  /**
-   * @param {(Error|string)} e
-   * @param {string=} message
-   */
-  static error(e, message) {
-    let details;
-    if (e instanceof Error) {
-      details = `${e.name}: ${e.message} (${e.stack})`;
-    } else {
-      details = e;
-      message = e;
-    }
-    console.error(details);
-    alert(message);
-  }
-
   /**
    * Degrees to radians
    * @param {number} degrees
diff --git a/js/test/alert.test.js b/js/test/alert.test.js
new file mode 100644
index 0000000..6c3ff4c
--- /dev/null
+++ b/js/test/alert.test.js
@@ -0,0 +1,143 @@
+/*
+ * μlogger
+ *
+ * Copyright(C) 2020 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 uAlert from '../src/alert.js';
+
+describe('Alert tests', () => {
+
+  const message = 'test message';
+  let alert;
+
+  afterEach(() => {
+    if (alert) {
+      alert.destroy();
+    }
+    document.body.innerText = '';
+  });
+
+  it('should create alert box with message', () => {
+    // when
+    alert = new uAlert(message);
+    const textEl = alert.box.firstChild;
+    // then
+    expect(textEl.innerText).toBe(message);
+  });
+
+  it('should create alert box with autoClose option', () => {
+    // given
+    const autoClose = 1;
+    const options = { autoClose }
+    // when
+    alert = new uAlert(message, options);
+    const textEl = alert.box.firstChild;
+    // then
+    expect(textEl.innerText).toBe(message);
+    expect(alert.autoClose).toBe(autoClose);
+  });
+
+  it('should create alert box with id option', () => {
+    // given
+    const id = 'testId';
+    const options = { id }
+    // when
+    alert = new uAlert(message, options);
+    const boxEl = alert.box;
+    const textEl = alert.box.firstChild;
+    // then
+    expect(textEl.innerText).toBe(message);
+    expect(boxEl.id).toBe(id);
+  });
+
+  it('should create alert box with class option', () => {
+    // given
+    const className = 'test_class';
+    const options = { class: className }
+    // when
+    alert = new uAlert(message, options);
+    const boxEl = alert.box;
+    const textEl = alert.box.firstChild;
+    // then
+    expect(textEl.innerText).toBe(message);
+    expect(boxEl.classList).toContain(className);
+  });
+
+  it('should render and destroy alert box', () => {
+    // given
+    const id = 'testId';
+    const options = { id }
+    alert = new uAlert(message, options);
+
+    // when
+    alert.render();
+    // then
+    expect(document.querySelector(`#${id}`)).not.toBeNull();
+
+    // when
+    alert.destroy();
+    // then
+    expect(document.querySelector(`#${id}`)).toBeNull();
+  });
+
+  it('should show and autoclose alert box', (done) => {
+    // given
+    const id = 'testId';
+    const options = { id: id, autoClose: 50 }
+
+    // when
+    alert = uAlert.show(message, options);
+    // then
+    expect(document.querySelector(`#${id}`)).not.toBeNull();
+
+    setTimeout(() => {
+      expect(document.querySelector(`#${id}`)).toBeNull();
+      done();
+    }, 100);
+  });
+
+  it('should close alert box on close button click', (done) => {
+    // given
+    const id = 'testId';
+    const options = { id }
+    alert = uAlert.show(message, options);
+    const closeButton = alert.box.querySelector('button');
+    // when
+    closeButton.click();
+    // then
+    setTimeout(() => {
+      expect(document.querySelector(`#${id}`)).toBeNull();
+      done();
+    }, 100);
+  });
+
+  it('should show error alert box', () => {
+    // when
+    alert = uAlert.error(message);
+    // then
+    expect(document.querySelector('.alert.error')).not.toBeNull();
+  });
+
+  it('should show toast alert box', () => {
+    // when
+    alert = uAlert.toast(message);
+    // then
+    expect(document.querySelector('.alert.toast')).not.toBeNull();
+    expect(alert.autoClose).toBeGreaterThan(0);
+  });
+
+});