Composer is a responsive One Column Omega child theme by Han.
https://themehall.com/composer-one-column-omega-child-theme
Frameworks · WordPress Theme
Get access to data on 10,419 websites that are Composer Customers. We know of 5,203 live websites using Composer and an additional 5,216 sites that used Composer historically and 2,457 websites in the United States.
Get a list of 10,419 websites using Composer which includes location information, hosting data, contact details, 5,203 currently live websites and an additional 1,999 domains that redirect to sites in this list. 5,216 sites that used this technology previously and 2,457 websites in the United States currently using Composer.