Apache is a free and open-source cross-platform web server software.
Contact Form 7 is an WordPress plugin which can manage multiple contact forms. The form supports Ajax-powered submitting, CAPTCHA, Akismet spam filtering.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
Open Graph is a protocol that is used to integrate any web page into the social graph.
PHP is a general-purpose scripting language used for web development.
Contact Form 7 v5.1 dropped support for reCaptcha v2 along with the [recaptcha] tag December 2018. This plugin brings that functionality back from Contact Form 7 5.0.5 and re-adds the [recaptcha] tag.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
WordPress is a free and open-source content management system written in PHP and paired with a MySQL or MariaDB database. Features include a plugin architecture and a template system.
Yoast SEO is a search engine optimisation plugin for WordPress and other platforms.