diff --git a/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/index-allow-http.html b/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/index-allow-http.html
index 5980fdef4a..069bbbb81e 100644
--- a/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/index-allow-http.html
+++ b/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/index-allow-http.html
@@ -60,6 +60,7 @@
     <link rel="preload" href="/js/vuetify-labs-3.7.5.min.js" as="script" />
     <link rel="preload" href="/js/vue-router-4.4.4.min.js" as="script" />
     <link rel="preload" href="/js/vuex-4.1.0.min.js" as="script" />
+    <script src="/js/browsercheck.js"></script>
     <script src="/js/auth.js"></script>
     <script src="/js/import-map-overrides-4.2.0.min.js"></script>
     <!-- systemjs homepage: https://github.com/systemjs/systemjs/releases
diff --git a/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/index.html b/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/index.html
index 57988a2c94..977e920a10 100644
--- a/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/index.html
+++ b/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/index.html
@@ -60,6 +60,7 @@
     <link rel="preload" href="/js/vuetify-labs-3.7.5.min.js" as="script" />
     <link rel="preload" href="/js/vue-router-4.4.4.min.js" as="script" />
     <link rel="preload" href="/js/vuex-4.1.0.min.js" as="script" />
+    <script src="/js/browsercheck.js"></script>
     <script src="/js/auth.js"></script>
     <script src="/js/import-map-overrides-4.2.0.min.js"></script>
     <!-- systemjs homepage: https://github.com/systemjs/systemjs/releases
diff --git a/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/js/browsercheck.js b/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/js/browsercheck.js
new file mode 100644
index 0000000000..916629a9d1
--- /dev/null
+++ b/openc3-cosmos-init/plugins/packages/openc3-tool-base/public/js/browsercheck.js
@@ -0,0 +1,102 @@
+/*
+# Copyright 2024, OpenC3, Inc.
+# All Rights Reserved.
+#
+# This program is free software; you can modify and/or redistribute it
+# under the terms of the GNU Affero General Public License
+# as published by the Free Software Foundation; version 3 with
+# attribution addendums as found in the LICENSE.txt
+#
+# 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 Affero General Public License for more details.
+#
+# This file may also be used under the terms of a commercial license
+# if purchased from OpenC3, Inc.
+*/
+
+;(function () {
+  const nagCount = 3
+
+  const minChromeVersion = 108 // November 2022
+  const minFirefoxVersion = 108 // December 2022
+  const minEdgeVersion = 108 // December 2022
+  const minSafariVersion = 16 // September 2022
+  const currentMinVersionString = `c${minChromeVersion},f${minFirefoxVersion},e${minEdgeVersion},s${minSafariVersion}`
+
+  const uaChrome = navigator.userAgent.match(/Chrome\/\d+/)
+  const uaFirefox = navigator.userAgent.match(/Firefox\/\d+/)
+  const uaEdge = navigator.userAgent.match(/Edg\/\d+/) // `/Edge\/\d+/` is Legacy Edge (pre-Chromium)
+  const uaSafari = navigator.userAgent.match(/Safari\/\d+/)
+
+  // Reset the nag counter when there are updates
+  const isNewMinVersion =
+    localStorage.lastCheckedBrowserVersions !== currentMinVersionString
+  const isNewUaString = localStorage.lastUaString !== navigator.userAgent
+  const isCounterUnset = parseInt(localStorage.browserCheckAlertCounter) === NaN
+  if (isNewMinVersion || isNewUaString || isCounterUnset) {
+    localStorage.lastCheckedBrowserVersions = currentMinVersionString
+    localStorage.lastUaString = navigator.userAgent
+    localStorage.browserCheckAlertCounter = 0
+  }
+
+  // Alert the user on page load a few times to get their attention,
+  // but then be quiet in case they need to use an unsupported browser
+  if (localStorage.browserCheckAlertCounter >= nagCount) {
+    return
+  }
+
+  function parseUaVersion(ua) {
+    return parseInt(ua.at(0).split('/').at(1))
+  }
+
+  /* Order matters here for Edge, Chrome, and Safari because their user-agent strings match each other.
+   * Edge: `Chrome/x Safari/x Edg/x`
+   * Chrome: `Chrome/x Safari/x`
+   * Safari: `Version/x Safari/x`
+   * Firefox: `Firefox/x`
+   *
+   * If we need to get any fancier than this, we should look into a parser library
+   * such as https://github.com/faisalman/ua-parser-js
+   */
+  if (uaEdge) {
+    const version = parseUaVersion(uaEdge)
+    if (version === NaN || version < minEdgeVersion) {
+      localStorage.browserCheckAlertCounter++
+      alert(
+        `It looks like you're using an unsupported version of Edge. Please update to version ${minEdgeVersion} or later.`,
+      )
+    }
+  } else if (uaChrome) {
+    const version = parseUaVersion(uaChrome)
+    if (version === NaN || version < minChromeVersion) {
+      localStorage.browserCheckAlertCounter++
+      alert(
+        `It looks like you're using an unsupported version of Chrome. Please update to version ${minChromeVersion} or later.`,
+      )
+    }
+  } else if (uaSafari) {
+    const uaSafariVersion = navigator.userAgent.match(/Version\/\d+/)
+    const version = parseUaVersion(uaSafariVersion)
+    if (version === NaN || version < minSafariVersion) {
+      localStorage.browserCheckAlertCounter++
+      alert(
+        `It looks like you're using an unsupported version of Safari. Please update to version ${minSafariVersion} or later.`,
+      )
+    }
+  } else if (uaFirefox) {
+    const version = parseUaVersion(uaFirefox)
+    if (version === NaN || version < minFirefoxVersion) {
+      localStorage.browserCheckAlertCounter++
+      alert(
+        `It looks like you're using an unsupported version of Firefox. Please update to version ${minFirefoxVersion} or later.`,
+      )
+    }
+  } else {
+    localStorage.browserCheckAlertCounter++
+    alert(
+      `It looks like you're using an unsupported browser. COSMOS might not work correctly. Please use Chrome (version ${minChromeVersion} or later) or Firefox (version ${minFirefoxVersion} or later).`,
+    )
+  }
+})()