Jenkins is an open source automation server written in Java. Jenkins helps to automate the non-human part of the software development process, with continuous integration and facilitating technical aspects of continuous delivery. It is a server-based system that runs in servlet containers such as Apache Tomcat.
AWS Lambda is an event-driven, serverless computing platform provided by Amazon as a part of Amazon Web Services. It lets clients run code without provisioning or managing servers.
Gmail is a free, advertising-supported email service offered as part of Google's G Suite, with 15GB of storage, color-coded inbox filters and unsend button.
Mailchimp Transactional Email (formerly Mandrill) is a reliable, scalable and secure delivery API for transactional emails from websites and applications.
Zabbix offers great performance for data gathering and can be scaled to very large environments. Distributed monitoring options are available with the use of Zabbix proxies. Zabbix comes with a web-based interface, secure user authentication and a flexible user permission schema.