HackerRank - HackerRank is a platform that allows companies to conduct interviews remotely to hire developers and for technical assessment purposes.

Mailman - Mailman is free software for managing electronic mail discussion and e-newsletter lists.

iMocha - Make intelligent talent decisions.

Mailman 3 - Dedicated Mailman 3 installation. Unlimited lists/configuration. Free subdomain at mailman3.com. Dedicated support for list admins.

Codility - Codility provides a SaaS platform with advanced validation, security and protection features to evaluate the skills of software engineers.

MailChimp - MailChimp is the best way to design, send, and share email newsletters.