diff --git a/webextension/background.js b/webextension/background.js
index e909c6b2c..5471e00a9 100644
--- a/webextension/background.js
+++ b/webextension/background.js
@@ -1,3 +1,172 @@
+const assignManager = {
+  closeableWindows: new Set([
+    "about:startpage",
+    "about:newtab",
+    "about:home",
+    "about:blank"
+  ]),
+  menuAssignId: "open-in-this-container",
+  menuRemoveId: "remove-open-in-this-container",
+  storageArea: browser.storage.local,
+
+  init() {
+    browser.tabs.onActivated.addListener((info) => {
+      browser.tabs.get(info.tabId).then((tab) => {
+        this.calculateContextMenu(tab);
+      }).catch((e) => {
+        throw e;
+      });
+    });
+
+    browser.windows.onFocusChanged.addListener(() => {
+      browser.tabs.query({active: true}).then((tab) => {
+        this.calculateContextMenu(tab);
+      }).catch((e) => {
+        throw e;
+      });
+    });
+
+    browser.runtime.onMessage.addListener((request) => {
+      if (request.neverAsk === true) {
+        this.storageArea.set({neverAsk: true});
+      }
+    });
+
+    browser.contextMenus.onClicked.addListener((info, tab) => {
+      const pageUrl = new window.URL(info.pageUrl);
+      const userContextId = this.getUserContextIdFromCookieStore(tab);
+      // Mapping ${pageUrl.origin} to ${userContextId}
+      if (userContextId) {
+        const originStoreKey = this.getOriginStoreKey(pageUrl);
+        let actionName;
+        let storageAction;
+        if (info.menuItemId === this.menuAssignId) {
+          actionName = "added";
+          storageAction = this.storageArea.set({[originStoreKey]: userContextId});
+        } else {
+          actionName = "removed";
+          storageAction = this.storageArea.remove([originStoreKey]);
+        }
+        storageAction.then(() => {
+          browser.notifications.create({
+            type: "basic",
+            title: "Containers",
+            message: `Successfully ${actionName} ${pageUrl.origin} to always open in this container`,
+            iconUrl: browser.extension.getURL("/img/onboarding-1.png")
+          });
+          this.calculateContextMenu(tab);
+        }).catch((e) => {
+          throw e;
+        });
+      }
+    });
+
+    browser.webRequest.onBeforeRequest.addListener((options) => {
+      if (options.frameId !== 0 || options.tabId === -1) {
+        return {};
+      }
+      const pageUrl = new window.URL(options.url);
+      const originStoreKey = this.getOriginStoreKey(pageUrl);
+      return Promise.all([
+        browser.tabs.get(options.tabId),
+        this.storageArea.get([originStoreKey, "neverAsk"])
+      ]).then(([tab, storage]) => {
+        const userContextId = this.getUserContextIdFromCookieStore(tab);
+        let neverAsk = false;
+        if (!(originStoreKey in storage)) {
+          return;
+        }
+        if ("neverAsk" in storage) {
+          neverAsk = storage.neverAsk;
+        }
+        const mapUserContextId = storage[originStoreKey];
+        if (userContextId === mapUserContextId) {
+          return {};
+        }
+
+        this.reloadPageInContainer(options.url, mapUserContextId, tab.index, neverAsk);
+        this.calculateContextMenu(tab);
+        // If the user just opened the tab, we can auto close it
+        if (this.closeableWindows.has(tab.url)) {
+          browser.tabs.remove(tab.id);
+        }
+        return {
+          cancel: true,
+        };
+      }).catch((e) => {
+        throw e;
+      });
+    },{urls: ["<all_urls>"], types: ["main_frame"]}, ["blocking"]);
+
+    browser.webRequest.onCompleted.addListener((options) => {
+      if (options.frameId !== 0 || options.tabId === -1) {
+        return {};
+      }
+      browser.tabs.get(options.tabId).then((tab) => {
+        this.calculateContextMenu(tab);
+      }).catch((e) => {
+        throw e;
+      });
+    },{urls: ["<all_urls>"], types: ["main_frame"]});
+  },
+
+  getOriginStoreKey(url) {
+    const storagePrefix = "originContainerMap@@_";
+    return `${storagePrefix}${url.origin}`;
+  },
+
+  getUserContextIdFromCookieStore(tab) {
+    if (!("cookieStoreId" in tab)) {
+      return false;
+    }
+    const cookieStore = tab.cookieStoreId;
+    const container = cookieStore.replace("firefox-container-", "");
+    if (container !== cookieStore) {
+      return container;
+    }
+    return false;
+  },
+
+  calculateContextMenu(tab) {
+    const cookieStore = this.getUserContextIdFromCookieStore(tab);
+    browser.contextMenus.remove(this.menuAssignId);
+    browser.contextMenus.remove(this.menuRemoveId);
+    // Ensure we have a cookieStore to assign to
+    // Ensure we are not an important about url
+    if (cookieStore && !this.closeableWindows.has(tab.url)) {
+      const originStoreKey = this.getOriginStoreKey(new URL(tab.url));
+      this.storageArea.get([originStoreKey]).then((store) => {
+        if (store[originStoreKey]) {
+          browser.contextMenus.create({
+            id: this.menuRemoveId,
+            title: "Remove Open in This Container",
+            contexts: ["all"],
+          });
+          return;
+        }
+        browser.contextMenus.create({
+          id: this.menuAssignId,
+          title: "Always Open in This Container",
+          contexts: ["all"],
+        });
+      }).catch((e) => {
+        throw e;
+      });
+    }
+  },
+
+  reloadPageInContainer(url, userContextId, index, neverAsk = false) {
+    const loadPage = browser.extension.getURL("confirm-page.html");
+    // If the user has explicitly checked "Never Ask Again" on the warning page we will send them straight there
+    if (neverAsk) {
+      browser.tabs.create({url, cookieStoreId: `firefox-container-${userContextId}`, index});
+    } else {
+      browser.tabs.create({url: `${loadPage}?url=${url}`, cookieStoreId: `firefox-container-${userContextId}`, index});
+    }
+  }
+};
+
+assignManager.init();
 
 const themeManager = {
   existingTheme: null,
diff --git a/webextension/confirm-page.html b/webextension/confirm-page.html
new file mode 100644
index 000000000..018143d27
--- /dev/null
+++ b/webextension/confirm-page.html
@@ -0,0 +1,33 @@
+<html>
+<head>
+  <meta http-equiv="content-type" content="text/html; charset=utf-8">
+  <title>Containers confirm navigation</title>
+  <link xmlns="http://www.w3.org/1999/xhtml" rel="stylesheet" href="chrome://browser/skin/aboutNetError.css" type="text/css" media="all" />
+  <link rel="stylesheet" href="/css/confirm-page.css" />
+</head>
+<body>
+  <main>
+    <div class="title">
+      <h1 class="title-text">Hey, we heard you liked containers!</h1>
+    </div>
+    <form id="redirect-form">
+      <p>
+        A page told us to open:
+      </p>
+      <div id="redirect-url"></div>
+      <p>
+        You asked for <span id="redirect-origin"></span> to always open in <span id="container-name">this</span> container, are you sure you want to confirm?<br />
+      </p>
+      <p>If you didn't mean to open this link or it looks suspicious don't open it.</p>
+      <br />
+      <input id="never-ask" type="checkbox" /><label for="never-ask">Never ask me this again</label>
+      <br />
+      <div class="button-container">
+        <button id="confirm" class="button primary">Take me there</button>
+      </div>
+    </form>
+  </main>
+
+  <script src="js/confirm-page.js"></script>
+</body>
+</html>
diff --git a/webextension/css/confirm-page.css b/webextension/css/confirm-page.css
new file mode 100644
index 000000000..ac9102535
--- /dev/null
+++ b/webextension/css/confirm-page.css
@@ -0,0 +1,33 @@
+/* General Rules and Resets */
+.title {
+  background-image: none;
+}
+
+main {
+  background: url(/img/onboarding-1.png) no-repeat;
+  background-position: -10px -15px;
+  background-size: 285px;
+  margin-inline-start: -285px;
+  padding-inline-start: 285px;
+}
+
+@media only screen and (max-width: 1300px) {
+  main {
+    background: none;
+  }
+
+  /* for a mid sized window we have enough for this but not our image */
+  .title {
+    background-image: url("chrome://global/skin/icons/info.svg");
+  }
+}
+
+html {
+  box-sizing: border-box;
+  font: message-box;
+}
+
+#redirect-url,
+#redirect-origin {
+  font-weight: bold;
+}
diff --git a/webextension/css/popup.css b/webextension/css/popup.css
index e2c8cd267..dd460d3ae 100644
--- a/webextension/css/popup.css
+++ b/webextension/css/popup.css
@@ -383,7 +383,7 @@ span ~ .panel-header-text {
 .panel-footer {
   align-items: center;
   background: #efefef;
-  block-size: 55px;
+  block-size: 54px;
   border-block-end: 1px solid #d8d8d8;
   color: #000;
   display: flex;
diff --git a/webextension/js/confirm-page.js b/webextension/js/confirm-page.js
new file mode 100644
index 000000000..2bcd15898
--- /dev/null
+++ b/webextension/js/confirm-page.js
@@ -0,0 +1,25 @@
+const redirectUrl = new URL(window.location).searchParams.get("url");
+document.getElementById("redirect-url").textContent = redirectUrl;
+const redirectOrigin = new URL(redirectUrl).origin;
+document.getElementById("redirect-origin").textContent = redirectOrigin;
+
+document.getElementById("redirect-form").addEventListener("submit", (e) => {
+  e.preventDefault();
+  const neverAsk = document.getElementById("never-ask").checked;
+  // Sending neverAsk message to background to store for next time we see this process
+  if (neverAsk) {
+    browser.runtime.sendMessage({
+      neverAsk: true
+    }).then(() => {
+      redirect();
+    }).catch(() => {
+      // Can't really do much here user will have to click it again
+    });
+  }
+  redirect();
+});
+
+function redirect() {
+  const redirectUrl = document.getElementById("redirect-url").textContent;
+  document.location.replace(redirectUrl);
+}
diff --git a/webextension/manifest.json b/webextension/manifest.json
index 3bb95da8c..72b1fef6f 100644
--- a/webextension/manifest.json
+++ b/webextension/manifest.json
@@ -19,8 +19,15 @@
   "homepage_url": "https://testpilot.firefox.com/",
 
   "permissions": [
+    "<all_urls>",
+    "activeTab",
     "cookies",
-    "tabs"
+    "contextMenus",
+    "notifications",
+    "storage",
+    "tabs",
+    "webRequestBlocking",
+    "webRequest"
   ],
 
   "browser_action": {