Shaun Plummer

Jenkins is easy to scale as demand increases. The declarative pipeline syntax bundled into the project repo is easy to read and maintain. As it's self hosted we don't need to worry about build time limits.

Bitbucket has good integration with Atlassian. Repositories can be organized into projects and the premium features offer controls around pull requests reviews and branch protection

Firebase is the go to solution for a backend environment for any iOS or Android mobile app. It's easy to setup and integrate. As well as containing a wide range of services to meet lots of different needs. The free service tier give you enough headroom to let you experiment and test before committing to the service.

Gradle and particularly the gradle wrapper is easy to use. Bundling all of the information required to build the project along side the source code is a real time saver compared to managing installed versions.