Website & Web App Security Scan, Malware, Firewall & Uptime — Defen.so

Scan any site for exposed secrets, weak headers, insecure cookies & API risks — including behind your login.

Scan any website for real security risks, right from your browser. No account needed to start. Defen.so is a Chrome extension that checks any page you visit for exposed secrets, weak security headers, insecure cookies, CSP and CORS gaps, and API risks — then lets you browse behind your login to reveal the authenticated attack surface a public scan can never see. Every finding is evidence-based, with a clear fix. Nothing is hallucinated. WHY A BROWSER EXTENSION, NOT JUST AN ONLINE SCANNER A public scanner only sees what an anonymous visitor sees. The most serious risks in a modern web app live behind the login — the admin pages, the internal APIs, the dashboards your users reach after they authenticate. An external pentest can't get there. The Defen.so extension scans from inside your own authenticated session. As you browse your app normally, it maps the real attack surface — the pages and endpoints that actually matter — and checks each one for exposed secrets, weak headers, and insecure handling. It runs locally, so your browsing never leaves your machine; only the findings you choose to sync ever reach your dashboard. WHAT THE EXTENSION CHECKS • Exposed secrets — API keys, access tokens, and credentials leaked in page source, inline scripts, or network calls, including private-key blocks. • Security headers — Missing or weak Content-Security-Policy, HSTS, X-Frame-Options, Referrer-Policy, X-Content-Type-Options, and more, graded against current best practice. • Insecure cookies — Session cookies missing Secure, HttpOnly, or SameSite — the exact ones that get stolen in an XSS or a man-in-the-middle. • CSP and CORS gaps — Over-permissive cross-origin rules and content-security holes that widen your attack surface. • API and endpoint risks — The endpoints a page talks to, flagged for authentication and exposure issues an external scan would miss. • Authenticated surface — Browse behind your login and the extension maps pages and APIs a public pentest cannot reach. • Virus and Malware detection. • Malicious & Suspicious Files Detection. HOW IT WORKS 1. Install and pin. Add the extension to Chrome and pin it to your toolbar. No account is needed to run your first scan. 2. Open any site, click the toolbar icon. The Defen.so side panel opens beside the page; click Scan and it runs a live scan of the current page and lists every finding with a fix — locally, so your browsing stays on your machine. 3. Connect for the full picture. Sign in to tie scans to your Defen.so sites, run authenticated pentests, and sync findings into one report alongside your uptime monitoring, repo secret scans, and attack logs. START WITH NO ACCOUNT, GROW WHEN YOU NEED TO Installing the scanner and running scans needs no account and no payment. A Defen.so plan unlocks deeper authenticated discovery, repo secret scans, AI fix analysis, and the remediation guidance for your most severe findings — plus uptime monitoring with instant alerts, a managed WAF, automated pentests, and a compliance generator, all in one dashboard. BUILT FOR DEVELOPERS, INDIE MAKERS, AND VIBE CODERS, And AGENCIES If you shipped an app fast — with an AI coding assistant or your own hands — the security section of your notes probably still says "add later." Defen.so is the fastest way to find what breaks most on modern web apps: a public .env file, an open database table, a downloadable .git directory, wide-open CORS, a missing content-security policy. Scan it in 30 seconds and fix the issues that matter before they ship. PRIVACY FIRST Scans run locally in your browser. The extension does not run in the background and does not intercept your traffic — it only scans when you open the panel and click scan on the current page. Only the findings you explicitly choose to sync are sent to your Defen.so dashboard. Your browsing history stays yours. WORKS EVERYWHERE CHROMIUM DOES Chrome, Edge, Brave, and Arc. It's a standard Manifest V3 extension — no special permissions beyond what a page scan needs. FREQUENTLY ASKED QUESTIONS Is this really free? Yes. Installing the extension and running scans is free, with no account required to start. Paid Defen.so plans add deeper authenticated discovery, repo scans, AI fix analysis, and monitoring. Does my browsing data leave my machine? No. Scans run locally in your browser. Only the findings you choose to sync are sent to your dashboard. How is this different from an online website security scanner? An online scanner only sees the public, anonymous view of a site. This extension scans from inside your authenticated session, revealing the pages and APIs behind your login that a public scan can never reach. Will it slow down my browsing? No. It only scans when you open the panel and click scan on the current page. It does not run in the background or intercept traffic. Which browsers are supported? Chrome and Chromium-based browsers — Edge, Brave, Arc. It's a standard Manifest V3 extension. Learn more: https://defen.so/chrome-extension-site-scanner Pricing: https://defen.so/pricing