CircleCI http://circleci.com as a continuous integration and deployment platform - they automate the build, test, and deploy process.
LaunchDarkly http://launchdarkly.com if you're looking to feature flag your builds and automate rollouts.
Gradle http://gradle.org is an open source build automation system that builds upon the concepts of Apache Ant and Apache Maven and introduces a Groovy-based domain-specific language (DSL) instead of the XML form used by Apache Maven of declaring the project configuration.
As a library author, supporting every 'flavor of the month' build tool is a waste of time/effort that takes away from improving the core.
JSPM. Like NPM but for client-side dependencies. It has built-in transpiling, es6-module support, and can build+minify bundles and sfx bundles.