diff --git a/book.toml b/book.toml
index 4ed9b191ee..c84cc630ff 100644
--- a/book.toml
+++ b/book.toml
@@ -68,6 +68,7 @@ additional-css = [
 ]
 additional-js = [
   "website/js/custom.js",
+  "website/js/goatcounter.js",
   "theme/pagetoc.js"
 ]
 no-section-label = false
diff --git a/theme/index.hbs b/theme/index.hbs
index fb365846a4..a7aa02309c 100644
--- a/theme/index.hbs
+++ b/theme/index.hbs
@@ -333,7 +333,7 @@
 
     </div>
 
-    <script data-goatcounter="https://agda-unimath.goatcounter.com/count" async src="//gc.zgo.at/count.js"></script>
+    <script data-goatcounter="https://agda-unimath.goatcounter.com/count" src="{{ path_to_root }}website/js/goatcounter.js"></script>
 </body>
 
 </html>
diff --git a/website/js/goatcounter.js b/website/js/goatcounter.js
new file mode 100644
index 0000000000..b532245ea3
--- /dev/null
+++ b/website/js/goatcounter.js
@@ -0,0 +1,304 @@
+// GoatCounter: https://www.goatcounter.com
+// This file is released under the ISC license: https://opensource.org/licenses/ISC
+(function () {
+  'use strict';
+
+  if (window.goatcounter && window.goatcounter.vars)
+    // Compatibility with very old version; do not use.
+    window.goatcounter = window.goatcounter.vars;
+  else window.goatcounter = window.goatcounter || {};
+
+  // Load settings from data-goatcounter-settings.
+  var s = document.querySelector('script[data-goatcounter]');
+  if (s && s.dataset.goatcounterSettings) {
+    try {
+      var set = JSON.parse(s.dataset.goatcounterSettings);
+    } catch (err) {
+      console.error('invalid JSON in data-goatcounter-settings: ' + err);
+    }
+    for (var k in set)
+      if (
+        [
+          'no_onload',
+          'no_events',
+          'allow_local',
+          'allow_frame',
+          'path',
+          'title',
+          'referrer',
+          'event',
+        ].indexOf(k) > -1
+      )
+        window.goatcounter[k] = set[k];
+  }
+
+  var enc = encodeURIComponent;
+
+  // Get all data we're going to send off to the counter endpoint.
+  var get_data = function (vars) {
+    var data = {
+      p: vars.path === undefined ? goatcounter.path : vars.path,
+      r: vars.referrer === undefined ? goatcounter.referrer : vars.referrer,
+      t: vars.title === undefined ? goatcounter.title : vars.title,
+      e: !!(vars.event || goatcounter.event),
+      s: [
+        window.screen.width,
+        window.screen.height,
+        window.devicePixelRatio || 1,
+      ],
+      b: is_bot(),
+      q: location.search,
+    };
+
+    var rcb, pcb, tcb; // Save callbacks to apply later.
+    if (typeof data.r === 'function') rcb = data.r;
+    if (typeof data.t === 'function') tcb = data.t;
+    if (typeof data.p === 'function') pcb = data.p;
+
+    if (is_empty(data.r)) data.r = document.referrer;
+    if (is_empty(data.t)) data.t = document.title;
+    if (is_empty(data.p)) data.p = get_path();
+
+    if (rcb) data.r = rcb(data.r);
+    if (tcb) data.t = tcb(data.t);
+    if (pcb) data.p = pcb(data.p);
+    return data;
+  };
+
+  // Check if a value is "empty" for the purpose of get_data().
+  var is_empty = function (v) {
+    return v === null || v === undefined || typeof v === 'function';
+  };
+
+  // See if this looks like a bot; there is some additional filtering on the
+  // backend, but these properties can't be fetched from there.
+  var is_bot = function () {
+    // Headless browsers are probably a bot.
+    var w = window,
+      d = document;
+    if (w.callPhantom || w._phantom || w.phantom) return 150;
+    if (w.__nightmare) return 151;
+    if (d.__selenium_unwrapped || d.__webdriver_evaluate || d.__driver_evaluate)
+      return 152;
+    if (navigator.webdriver) return 153;
+    return 0;
+  };
+
+  // Object to urlencoded string, starting with a ?.
+  var urlencode = function (obj) {
+    var p = [];
+    for (var k in obj)
+      if (
+        obj[k] !== '' &&
+        obj[k] !== null &&
+        obj[k] !== undefined &&
+        obj[k] !== false
+      )
+        p.push(enc(k) + '=' + enc(obj[k]));
+    return '?' + p.join('&');
+  };
+
+  // Show a warning in the console.
+  var warn = function (msg) {
+    if (console && 'warn' in console) console.warn('goatcounter: ' + msg);
+  };
+
+  // Get the endpoint to send requests to.
+  var get_endpoint = function () {
+    var s = document.querySelector('script[data-goatcounter]');
+    if (s && s.dataset.goatcounter) return s.dataset.goatcounter;
+    return goatcounter.endpoint || window.counter; // counter is for compat; don't use.
+  };
+
+  // Get current path.
+  var get_path = function () {
+    var loc = location,
+      c = document.querySelector('link[rel="canonical"][href]');
+    if (c) {
+      // May be relative or point to different domain.
+      var a = document.createElement('a');
+      a.href = c.href;
+      if (
+        a.hostname.replace(/^www\./, '') ===
+        location.hostname.replace(/^www\./, '')
+      )
+        loc = a;
+    }
+    return loc.pathname + loc.search || '/';
+  };
+
+  // Run function after DOM is loaded.
+  var on_load = function (f) {
+    if (document.body === null)
+      document.addEventListener(
+        'DOMContentLoaded',
+        function () {
+          f();
+        },
+        false
+      );
+    else f();
+  };
+
+  // Filter some requests that we (probably) don't want to count.
+  goatcounter.filter = function () {
+    if (
+      'visibilityState' in document &&
+      document.visibilityState === 'prerender'
+    )
+      return 'visibilityState';
+    if (!goatcounter.allow_frame && location !== parent.location)
+      return 'frame';
+    if (
+      !goatcounter.allow_local &&
+      location.hostname.match(
+        /(localhost$|^127\.|^10\.|^172\.(1[6-9]|2[0-9]|3[0-1])\.|^192\.168\.|^0\.0\.0\.0$)/
+      )
+    )
+      return 'localhost';
+    if (!goatcounter.allow_local && location.protocol === 'file:')
+      return 'localfile';
+    if (localStorage && localStorage.getItem('skipgc') === 't')
+      return 'disabled with #toggle-goatcounter';
+    return false;
+  };
+
+  // Get URL to send to GoatCounter.
+  window.goatcounter.url = function (vars) {
+    var data = get_data(vars || {});
+    if (data.p === null)
+      // null from user callback.
+      return;
+    data.rnd = Math.random().toString(36).substr(2, 5); // Browsers don't always listen to Cache-Control.
+
+    var endpoint = get_endpoint();
+    if (!endpoint) return warn('no endpoint found');
+
+    return endpoint + urlencode(data);
+  };
+
+  // Count a hit.
+  window.goatcounter.count = function (vars) {
+    var f = goatcounter.filter();
+    if (f) return warn('not counting because of: ' + f);
+    var url = goatcounter.url(vars);
+    if (!url) return warn('not counting because path callback returned null');
+    navigator.sendBeacon(url);
+  };
+
+  // Get a query parameter.
+  window.goatcounter.get_query = function (name) {
+    var s = location.search.substr(1).split('&');
+    for (var i = 0; i < s.length; i++)
+      if (s[i].toLowerCase().indexOf(name.toLowerCase() + '=') === 0)
+        return s[i].substr(name.length + 1);
+  };
+
+  // Track click events.
+  window.goatcounter.bind_events = function () {
+    if (!document.querySelectorAll)
+      // Just in case someone uses an ancient browser.
+      return;
+
+    var send = function (elem) {
+      return function () {
+        goatcounter.count({
+          event: true,
+          path: elem.dataset.goatcounterClick || elem.name || elem.id || '',
+          title:
+            elem.dataset.goatcounterTitle ||
+            elem.title ||
+            (elem.innerHTML || '').substr(0, 200) ||
+            '',
+          referrer:
+            elem.dataset.goatcounterReferrer ||
+            elem.dataset.goatcounterReferral ||
+            '',
+        });
+      };
+    };
+
+    Array.prototype.slice
+      .call(document.querySelectorAll('*[data-goatcounter-click]'))
+      .forEach(function (elem) {
+        if (elem.dataset.goatcounterBound) return;
+        var f = send(elem);
+        elem.addEventListener('click', f, false);
+        elem.addEventListener('auxclick', f, false); // Middle click.
+        elem.dataset.goatcounterBound = 'true';
+      });
+  };
+
+  // Add a "visitor counter" frame or image.
+  window.goatcounter.visit_count = function (opt) {
+    on_load(function () {
+      opt = opt || {};
+      opt.type = opt.type || 'html';
+      opt.append = opt.append || 'body';
+      opt.path = opt.path || get_path();
+      opt.attr = opt.attr || {
+        width: '200',
+        height: opt.no_branding ? '60' : '80',
+      };
+
+      opt.attr['src'] =
+        get_endpoint() + 'er/' + enc(opt.path) + '.' + enc(opt.type) + '?';
+      if (opt.no_branding) opt.attr['src'] += '&no_branding=1';
+      if (opt.style) opt.attr['src'] += '&style=' + enc(opt.style);
+      if (opt.start) opt.attr['src'] += '&start=' + enc(opt.start);
+      if (opt.end) opt.attr['src'] += '&end=' + enc(opt.end);
+
+      var tag = { png: 'img', svg: 'img', html: 'iframe' }[opt.type];
+      if (!tag) return warn('visit_count: unknown type: ' + opt.type);
+
+      if (opt.type === 'html') {
+        opt.attr['frameborder'] = '0';
+        opt.attr['scrolling'] = 'no';
+      }
+
+      var d = document.createElement(tag);
+      for (var k in opt.attr) d.setAttribute(k, opt.attr[k]);
+
+      var p = document.querySelector(opt.append);
+      if (!p) return warn('visit_count: append not found: ' + opt.append);
+      p.appendChild(d);
+    });
+  };
+
+  // Make it easy to skip your own views.
+  if (location.hash === '#toggle-goatcounter') {
+    if (localStorage.getItem('skipgc') === 't') {
+      localStorage.removeItem('skipgc', 't');
+      alert('GoatCounter tracking is now ENABLED in this browser.');
+    } else {
+      localStorage.setItem('skipgc', 't');
+      alert(
+        'GoatCounter tracking is now DISABLED in this browser until ' +
+          location +
+          ' is loaded again.'
+      );
+    }
+  }
+
+  if (!goatcounter.no_onload)
+    on_load(function () {
+      // 1. Page is visible, count request.
+      // 2. Page is not yet visible; wait until it switches to 'visible' and count.
+      // See #487
+      if (
+        !('visibilityState' in document) ||
+        document.visibilityState === 'visible'
+      )
+        goatcounter.count();
+      else {
+        var f = function (e) {
+          if (document.visibilityState !== 'visible') return;
+          document.removeEventListener('visibilitychange', f);
+          goatcounter.count();
+        };
+        document.addEventListener('visibilitychange', f);
+      }
+
+      if (!goatcounter.no_events) goatcounter.bind_events();
+    });
+})();