On-page Regression check tool
Modern websites are developed and deployed using DevOps operations at different environment like, Development, Staging, Live. 

Elite Site Optimizer crawler's prime job is to crawl the given website on every week to identify the on-page errors on the website that includes missing title, missing H1, missing description, duplicate title, duplicate description, missing canonical, mismatch canonical, multiple h1 and more. 

Website codes are constantly updated to the LIVE environment from other environments like Staging. It is natural when there are on-page seo issues that prevailing in staging or dev environment may get updated to the LIVE website. 

Staging vs. LIVE or Different period crawl data compare
Regression Check tool is a feature in ESO crawler that will crawl the specified environment regularly and keep the issue information in the database. This Regression check tool helps the users to compare the on-page SEO issues between these environments like Staging vs. Live or to compare the issue summary/ detailed issues, of same environment at different time period to help understand which updates brought on-page seo changes to the website, helps to locate the problem quickly and resolve them in a matter of time