kevin

This plugin enables WordPress to send HSTS header to browser
IMPORTANT NOTE: This plugin won’t work if you use any WordPress caching plugin. If this is the case, then update your .htaccess file to specify HSTS header.
HTTP Strict Transport Security (HSTS) is a web security policy mechanism that helps to protect websites against protocol downgrade attacks and cookie hijacking.
It allows web servers to declare that web browsers (or other complying user agents) should interact with it using only secure HTTPS connections, and never via the insecure HTTP protocol

Simple HSTS Preload

This plugin enables HSTS header on WordPress

Jay Suthar

BoundaryGuard Headers enforces modern HTTP security headers to harden your WordPress site against XSS, clickjacking, mixed content, and cross-origin attacks.
Key Features:
<ul>
<li>Essential Protection: Adds X-Frame-Options, X-Content-Type-Options, Referrer-Policy, and Permissions-Policy to reduce attack surface and prevent clickjacking.</li>
<li>HSTS (Strict Transport Security): Forces HTTPS connections to help prevent protocol downgrade and man-in-the-middle attacks.</li>
<li>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.</li>
<li>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.</li>
<li>CSP Report-Only Mode: Test your policy safely without blocking content.</li>
<li>Server Header Hardening: Removes or limits exposure of headers such as <code>X-Powered-By</code> and <code>Server</code>.</li>
<li>Lightweight and Fast: Uses PHP headers for broad server compatibility and minimal performance impact.</li>
<li>No <code>.htaccess</code> Editing Required: Works without modifying server configuration files.</li>
</ul>
Designed for developers and site owners who want stronger security without unnecessary complexity.
<h3>External Services</h3>
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/]

BoundaryGuard Headers

Automatically enforces essential HTTP security headers to protect your site from XSS, clickjacking, and protocol downgrade attacks.

Simple HSTS Preload vs BoundaryGuard Headers