Ayesh Karunaratne

This plugin ensures that when users of your website (including site administrators), the browsers are instructed to clear all residue such as cookies and caches to enhance the security.
<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Clear-Site-Data" rel="nofollow ugc"><code>Clear-Site-Data</code> HTTP header</a> is sent when a user logs out, which supported browsers will react by removing all existing cookies, cache, and other storage. It will not remove saved passwords, permissions, adblocker rules, and other data that are supposed to be permanent.
This plugin prevents possible security vulnerabilities such as clicking the “Back” button in the browser after logging out revealing the pages that should not have been accessible after logging out. Furthermore, this cleans the browser cache, which prevents accessing authenticated media assets (such as purchased images) from the browser cache of a victim.

Clear Logout

A tiny WordPress plugin to clear all browser data related to the site upon logout (With Clear-Site-Data header).

Julio Potier

Grégory Viguier

With this plugin you can now add a real log in/logout item menu with autoswitch when user is logged in or not. 
Nonce token is present on logout item. 
2 titles, one for ‘log in’ and one for ‘logout’ can be set up. 
Also, you can set the redirecion page you want, just awesome.

Login Logout Menu

This plugin (still) works great.

However be aware that it's not compatible with PHP 8 or newer, the latest PHP version this plugin will work with is 7.4. This is due to its use of create_function, which has been deprecated since PHP 7.2 and removed as of PHP 8. This should be replaced with an anonymous function, which is easy enough. But I haven't tested this myself, so I don't know if that's the only incompatibility with PHP 8+.

Works great, but...

You can now add a correct login & logout link in your WP menus.

Clear Logout vs Login Logout Menu