Identify and fix mixed content issues that weaken your HTTPS security. Use the interactive scanner below to analyze HTML code for mixed content, review common issues with the checklist, and learn how to fix every type of mixed content problem.
Mixed content occurs when an HTTPS page loads sub-resources (scripts, images, stylesheets, etc.) over insecure HTTP connections. This creates a security gap because the HTTP resources can be intercepted and modified by attackers on the network, undermining the protection that HTTPS provides. Even if your website has a valid SSL certificate, mixed content weakens the entire security chain.
This is especially relevant for websites served through port-forwarded home servers or any site where traffic passes through shared networks. Without proper HTTPS enforcement, an attacker on the same network — or anyone performing a man-in-the-middle attack — can inject malicious content into HTTP-loaded resources. Protect your browsing by using DNS over HTTPS and a VPN on your router.
Browsers distinguish between two categories of mixed content, treating each differently in terms of blocking behavior and security risk:
| Type | Resources | Risk | Browser Behavior |
|---|---|---|---|
| Active (Critical) | Scripts, stylesheets, iframes, XHR/fetch, fonts | Can modify the entire page, steal data, redirect users | Blocked by default in all modern browsers |
| Passive (Warning) | Images, video, audio | Can replace visual content but cannot execute code | Loaded with console warning; some browsers auto-upgrade |
Pro Tip: Modern browsers (Chrome 80+, Firefox 80+) are increasingly auto-upgrading passive mixed content from HTTP to HTTPS. However, you should not rely on this — if the HTTPS version does not exist, the resource will fail to load. Always fix mixed content at the source by updating URLs in your code. Use the CSP header
upgrade-insecure-requestsas a safety net, not a primary fix.
Mixed content issues often arise during HTTPS migration or when integrating third-party resources. Here are the most frequent causes:
http:// URLs that were not updated during migration.Fixing mixed content involves updating all HTTP resource URLs to HTTPS. Here are the approaches for different scenarios:
<!-- Before (mixed content) -->
<img src="http://cdn.example.com/image.jpg">
<!-- After (protocol-relative) -->
<img src="//cdn.example.com/image.jpg">
<!-- Best practice (explicit HTTPS) -->
<img src="https://cdn.example.com/image.jpg"><!-- Add to HTML head or server response headers -->
<meta http-equiv="Content-Security-Policy" content="upgrade-insecure-requests">
# Or as a server header (Nginx)
add_header Content-Security-Policy "upgrade-insecure-requests" always;# Replace all HTTP URLs in WordPress database
wp search-replace 'http://yourdomain.com' 'https://yourdomain.com' --dry-run
wp search-replace 'http://yourdomain.com' 'https://yourdomain.com'For comprehensive HTTPS security, combine mixed content fixes with proper HTTP security headers and strong WiFi encryption.
https:// URLs are preferred because they work correctly in all contexts, including when pages are loaded from local files or non-HTTP contexts. Always use explicit HTTPS URLs in new code.
Router admin panels and network management interfaces are often guilty of mixed content issues, especially on older devices. When you access your router at 192.168.1.1, the admin interface may load resources (firmware update checks, help documentation, external scripts) over HTTP even if you are connected via HTTPS.
| Device Type | Common Issue | Risk |
|---|---|---|
| Router admin panels | Firmware check over HTTP | Fake update could install malicious firmware |
| NAS devices | External help links over HTTP | Help page could be replaced with phishing |
| IP cameras | Video stream over HTTP | Stream could be intercepted or replaced |
| Smart home hubs | Cloud API calls over HTTP | Commands could be intercepted or injected |
This is another reason to keep your router firmware updated and to access admin panels from a secure, segmented network. Use our Port Checker to verify that your admin panel is not exposed to the internet.
Beyond the HTML scanner above, use these methods to detect mixed content on live websites:
# Open DevTools (F12) → Console tab
# Mixed content warnings appear as:
# "Mixed Content: The page was loaded over HTTPS, but requested
# an insecure resource 'http://...' This request was blocked."# Add report-only CSP header to collect violations
Content-Security-Policy-Report-Only: default-src https:; report-uri /csp-reportCSP reporting is the most thorough method because it catches issues across all pages without manually visiting each one. See our HTTP Headers Checker for more on implementing CSP. Also check your DNS configuration to ensure all subdomains resolve correctly over HTTPS.
Mixed content does not just affect security — it also impacts your website's search engine ranking and user trust:
https:// URLs — avoid protocol-relative URLs in new code.upgrade-insecure-requests directive as a safety net during HTTPS migration.Active mixed content (scripts, iframes, stylesheets) is blocked by all modern browsers, which can break functionality. Passive mixed content (images, video) may still load but with a console warning. Fixing all mixed content ensures your site works correctly for all visitors.
For large sites, use CSP reporting with the report-uri directive to collect all violations across all pages. You can also use crawling tools that check every page. Our HTML scanner above works for individual pages — paste the source code of any page to check it.
The CSP upgrade-insecure-requests directive tells browsers to automatically upgrade HTTP requests to HTTPS. However, if the HTTPS version of a resource does not exist, it will fail to load. Use it as a safety net during migration, but always update the actual URLs in your code for a permanent fix.
Regular anchor links (<a href="http://...">) are not considered mixed content because they navigate away from the current page rather than loading a sub-resource into it. However, it is still best practice to use HTTPS links everywhere for consistency and to avoid redirect chains.
Yes. If you access any HTTPS website with mixed content while on an insecure network (public WiFi, compromised router), an attacker can modify the HTTP resources. This is why it is important to secure your home WiFi and use a VPN on untrusted networks.
Yes. Many router admin interfaces at 192.168.1.1 load resources over HTTP. This is a security risk especially if you access the admin panel over WiFi. Update your firmware to get the latest security fixes for the admin interface.
Use browser DevTools to check for mixed content warnings in the console. You can also add a Content-Security-Policy-Report-Only header in your staging environment to collect violations without blocking any content. This lets you identify and fix issues before going live.
About Tommy N.
Tommy is the founder of RouterHax and a network engineer with 10+ years of experience in home and enterprise networking. He specializes in router configuration, WiFi optimization, and network security. When not writing guides, he's testing the latest mesh WiFi systems and helping readers troubleshoot their home networks.
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