Travis CI is an open source, hosted continuous integration and delivery service used to build and test GitHub projects. It is virtually identical to CircleCI, but with some minor differences.
Compared to CircleCI, its main advantages are that it can run tests on Linux and Mac at the same time, supports more languages out of the box, and has a build matrix, that allows you to run tests with different versions of languages and packages. In some cases, Travis CI has been criticized for slow provisioning time and instability.