Widely-used, free, and open-source software with worldwide support available:
Linux operating system.
MySQL database server.
PHP programming language.
Twig template processing for PHP.
SASS cascade style sheets extension.
PUG template processing for HTML.
Open source initiative support
Cetera is the creator and maintainer of the free open source content management system Cetera CMS. This software product helps to start your internet sales in 5 minutes. Cetera CMS avaiable under the MIT-license. Product may be downloaded from GitHub. Also you can create website or webshop in the cloud for free.
Development and production servers in US and European data-centers.
Atlassian Jira and GitLab as primary development tools.
Google Mail, Google Hangouts and Skype for communications.