Drupal has a lot of module alternatives, but definitely, there is one that remarks as the most popular one out there: Real-time SEO for Drupal. By far, this is the Best Drupal SEO module you will find, either 7 or 8.
The Best Drupal SEO Module
Real Time SEO module is a neat integration with the popular CMS system and https://github.com/Yoast/YoastSEO.js library. It is an amazing natural way of encouraging your users to build high-quality content in an NON-SPAMMY way that will improve your actual writing skills and your SEO knowledge.
As specified on the module page:
This module checks things you're bound to forget. It checks, whether your posts are long enough, if you've written a meta description and if that meta description contains your focus keyword, if you've used any subheadings within your post, etc. etc.
This real-time page analysis makes sure that your content is the type of content search engines and users will love!
More Drupal SEO modules out there
Improving your SEO? Surely Drupal can do it, but it requires a lot of work for site building, setup and process to finally make it work. The following list of modules will help you to optimize your website, improve your organic traffic and leverage new clients into your sites:
XML Sitemap: https://www.drupal.org/project/xmlsitemap
Want to go further?
Surely there are many alternatives, but the following book is an amazing guide for improving your Drupal SEO skills: https://www.drupal.org/node/2838399