What are some alternatives?
Jenkins - Jenkins is an open-source continuous integration server with 300+ plugins to support all kinds of software development
Ansible - Radically simple configuration-management, application deployment, task-execution, and multi-node orchestration engine
Travis CI - Focus on writing code. Let Travis CI take care of running your tests and deploying your apps.
SaltStack - SaltStack event-driven automation delivers security, cloud and configuration management for a software-defined world and enterprise complexity and scale.
CircleCI - CircleCI gives web developers powerful Continuous Integration and Deployment with easy setup and maintenance.
Chef - Automation for all of your technology. Overcome the complexity and rapidly ship your infrastructure and apps anywhere with automation.