diff --git a/pywb/static/loading-spinner/loading-spinner.js b/pywb/static/loading-spinner/loading-spinner.js
new file mode 100644
index 00000000..eddaee34
--- /dev/null
+++ b/pywb/static/loading-spinner/loading-spinner.js
@@ -0,0 +1,156 @@
+class LoadingSpinner {
+  static #instanceCount = 0;
+  constructor(config={}) {
+    this.config = {initialState:true, animationDuration:500, text:'Loading...', ...config};
+
+    if (LoadingSpinner.#instanceCount > 0) {
+      throw new Error('Cannot make a second loading spinner (aka progress indicator)');
+    }
+    LoadingSpinner.#instanceCount++;
+
+
+    const uuid = Math.floor(Math.random()*1000);
+    this.classes = {
+      el: `loading-spinner-${uuid}`,
+      mask: `loading-spinner-mask-${uuid}`,
+      hidden: `hidden-${uuid}`,
+      spinning: `spinning-${uuid}`
+    };
+
+    this.state = config.initialState;
+    this.addStyles();
+    this.addDom();
+  }
+
+  toggle() {
+    if (this.state) {
+      this.setOn();
+    } else {
+      this.setOff();
+    }
+  }
+
+  setOn() {
+    this.state = true;
+    this.el.classList.remove(this.classes.hidden);
+    setTimeout(function setSpinning() {
+      this.el.classList.add(this.classes.spinning);
+    }.bind(this), 10);
+  }
+
+  setOff() {
+    this.state = false;
+    this.el.classList.remove(this.classes.spinning);
+    setTimeout(function setHidden() {
+      this.el.classList.add(this.classes.hidden);
+    }.bind(this), this.config.animationDuration);
+  }
+
+  addDom() {
+    const text = this.config.text;
+    const dom = `
+<div class="${this.classes.mask} ${this.classes[this.config.initialState ? 'spinning':'hidden']}">
+  <div class="${this.classes.el}">
+    <div data-loading-spinner="circle1"></div>
+    <div data-loading-spinner="circle2"></div>
+    <div data-loading-spinner="circle3"></div>
+    <div data-loading-spinner="circle4"></div>
+    <span data-loading-spinner="text">${text}</span>
+  </div>
+</div>`;
+    const wrapEl = document.createElement('div');
+    wrapEl.innerHTML = dom;
+    this.el = wrapEl.firstElementChild;
+    document.getElementsByTagName('body')[0].appendChild(this.el);
+  }
+
+  addStyles() {
+    const duration = this.config.animationDuration;
+    const stylesheetEl = document.createElement('style');
+    document.head.appendChild(stylesheetEl);
+
+    const rules = [`
+.${this.classes.mask} {
+    position: fixed;
+    top: 0;
+    left: 0;
+    width: 100vw;
+    height: 100vh;
+    z-index: 900;
+
+    display: flex;
+    justify-content: center;
+    align-items: center;
+
+    background-color: rgba(255,255,255, .85);
+
+    opacity: 0;
+    transition: opacity ${duration}ms ease-in;
+}`,`
+.${this.classes.mask}.${this.classes.spinning} {
+    opacity: 1;
+}`,`
+.${this.classes.mask}.${this.classes.hidden} {
+    display: none;
+}`,`
+.${this.classes.el} {
+    position: relative;
+    display: flex;
+    justify-content: center;
+    align-items: center;
+    width: 200px;
+    height: 200px;
+}`,`
+[data-loading-spinner^=circle] {
+    position: absolute;
+    margin: 0;
+    border-radius: 50%;
+    border-left-color: transparent;
+    border-right-color: transparent;
+}`,`
+[data-loading-spinner=circle1] {
+    border: 3px solid #444444;/* #0D4B9F; */
+    width: 70%;
+    height: 70%;
+    animation: rotate 2s cubic-bezier(0.26, 1.36, 0.74, -0.29) infinite;
+}`,`
+[data-loading-spinner=circle2] {
+    border: 3px solid #ddd;/* #E0EDFF; */
+    width: 80%;
+    height: 80%;
+    animation: rotateReverse 2s cubic-bezier(0.26, 1.36, 0.74, -0.29) infinite;
+}`,`
+[data-loading-spinner=circle3] {
+    border: 3px solid #656565;/* #005CDC; */
+    width: 90%;
+    height: 90%;
+    animation: rotate 2s cubic-bezier(0.26, 1.36, 0.74, -0.29) infinite;
+}`,`
+[data-loading-spinner=circle4] {
+    border: 3px solid #aaa; /* #94B6E5; */
+    width: 100%;
+    height: 100%;
+    animation: rotateReverse 2s cubic-bezier(0.26, 1.36, 0.74, -0.29) infinite;
+}`,`
+@keyframes rotate {
+    from {
+        transform: rotateZ(-360deg)
+    }
+    to {
+        transform: rotateZ(0deg)
+    }
+}`,`
+@keyframes rotateReverse {
+    from {
+        transform: rotateZ(360deg)
+    }
+    to {
+        transform: rotateZ(0deg)
+    }
+}`,`
+[data-loading-spinner=text] {
+    font-size: 15px;
+}`];
+      rules.forEach(rule => stylesheetEl.sheet.insertRule(rule));
+  }
+}
\ No newline at end of file
diff --git a/pywb/static/loading-spinner/test.html b/pywb/static/loading-spinner/test.html
new file mode 100644
index 00000000..49a68ca0
--- /dev/null
+++ b/pywb/static/loading-spinner/test.html
@@ -0,0 +1,12 @@
+<html>
+<head>
+<script src="loading-spinner.js"></script>
+</head>
+<body>
+<button onclick="loadingSpinner.setOn()">load...</button>
+<script>
+    const loadingSpinner = new LoadingSpinner();
+    loadingSpinner.el.addEventListener('click', e => loadingSpinner.setOff());
+</script>
+</body>
+</html>
\ No newline at end of file