Java

// Replace with your actual Google Safe Browsing API key
const API_KEY = "YOUR_GOOGLE_SAFE_BROWSING_API_KEY";

chrome.runtime.onMessage.addListener((request, sender, sendResponse) => {
  if (request.action === "checkUrl") {
    const urlToCheck = request.url;

    fetch("https://safebrowsing.googleapis.com/v4/threatMatches:find?key=" + API_KEY, {
      method: "POST",
      body: JSON.stringify({
        client: {
          clientId:      "beaconsafe-extension",
          clientVersion: "2.0"
        },
        threatInfo: {
          threatTypes:      ["MALWARE", "SOCIAL_ENGINEERING", "UNWANTED_SOFTWARE", "POTENTIALLY_HARMFUL_APPLICATION"],
          platformTypes:    ["ANY_PLATFORM"],
          threatEntryTypes: ["URL"],
          threatEntries: [
            { url: urlToCheck }
          ]
        }
      }),
      headers: {
        "Content-Type": "application/json"
      }
    })
    .then(response => response.json())
    .then(data => {
      if (data && data.matches) {
        sendResponse({ unsafe: true });
      } else {
        sendResponse({ unsafe: false });
      }
    })
    .catch(error => {
      console.error("Safe Browsing API error:", error);
      sendResponse({ unsafe: false });
    });

    // Indicate async response
    return true;
  }
});
3. content.js
JavaScript
// Only check top-level frame
if (window.top === window.self) {
  chrome.runtime.sendMessage(
    { action: "checkUrl", url: window.location.href },
    (response) => {
      if (response && response.unsafe) {
        document.body.innerHTML = `
          <div style="background: #b30000; color: #fff; height: 100vh; display: flex; flex-direction: column; align-items: center; justify-content: center;">
            <h1 style="font-size:3em;">⛔ BEACONSAFE ALERT</h1>
            <p style="font-size:1.5em;">This webpage is flagged as unsafe and may try to hack you!</p>
            <p style="font-size:1.2em;">We recommend closing this page immediately.</p>
          </div>
        `;
        document.title = "⚠️ Unsafe Webpage Blocked";
      }
    }
  );
}