Contributor Covenant
A Code of Conduct for (Open Source) Communities. According to Wikipedia, the Contributor Covenant is used in prominent projects including Linux, Ruby on Rails, Swift, Go, and JRuby. Relevant signers include Google, Apple, Microsoft, Intel, Eclipse and GitLab.
In 2016 GitHub added a feature to streamline the addition of the Contributor Covenant to an open source project and the Ruby library manager Bundler also has an option to add the Contributor Covenant to software programs that its users create: https://www.contributor-covenant.org.