“http-headers”

This plugin Sends Header Status 401 When Login Fails. Edit

Adds Security Header to WordPress

Add preload link headers for scripts and styles.

Add missing cache in header.

WordPress plugin which sends HTTP caching headers

A clear and simple HTTP cache drop-in plugin for WordPress which only set adequate HTTP headers. No UI, no extras.

WordPress plugin to add privacy-focused HTTP security headers with sensible defaults that won't break your site.