BoundaryGuard Headers enforces modern HTTP security headers to harden your WordPress site against XSS, clickjacking, mixed content, and cross-origin attacks.

Key Features:

Essential Protection: Adds X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy to reduce attack surface and prevent clickjacking.
HSTS (Strict Transport Security): Forces HTTPS connections to help prevent protocol downgrade and man-in-the-middle attacks.
Advanced Isolation (COOP/COEP): Enables Cross-Origin-Opener-Policy and Cross-Origin-Embedder-Policy to improve cross-origin isolation and mitigate certain side-channel attacks.
Content Security Policy (CSP): One of the strongest defenses against XSS. Includes a dashboard-based CSP builder with preset options to whitelist trusted sources for scripts, styles, images, and more.
CSP Report-Only Mode: Test your policy safely without blocking content.
Server Header Hardening: Removes or limits exposure of headers such as X-Powered-By and Server.
Lightweight and Fast: Uses PHP headers for broad server compatibility and minimal performance impact.
No .htaccess Editing Required: Works without modifying server configuration files.

Designed for developers and site owners who want stronger security without unnecessary complexity.

External Services

This plugin provides a Content Security Policy (CSP) builder. To assist users, it includes “Preset Buttons” that allow users to quickly add domain names to their own CSP whitelist.

This plugin DOES NOT connect to, load data from, or send data to these services automatically. The following third-party domains are referenced as presets within the admin dashboard for whitelisting purposes:
* Google Analytics (www.google-analytics.com) – Used for tracking whitelisting. [Privacy: https://policies.google.com/privacy]
* Google Tag Manager (www.googletagmanager.com) – Used for tag management. [Privacy: https://policies.google.com/privacy]
* Stripe (js.stripe.com, api.stripe.com) – Used for payment processing. [Privacy: https://stripe.com/privacy]
* Facebook (www.facebook.com, connect.facebook.net) – Used for social embeds. [Privacy: https://www.facebook.com/policy.php]
* YouTube (www.youtube.com, i.ytimg.com) – Used for video embeds. [Privacy: https://policies.google.com/privacy]
* Vimeo (player.vimeo.com) – Used for video embeds. [Privacy: https://vimeo.com/privacy]
* Gravatar (secure.gravatar.com) – Used for user avatars. [Privacy: https://automattic.com/privacy/]