gistfile1.txt

travis-ci
  ubuntu
  macOS

circleci
  ubuntu
  macOS

jenkins
  unclear but docker based

appveyor
  windows server 2012/2016
  cool for windows supproting software I guess

codeship
  ubuntu

droneio
  open source
  docker based
  written in golang

semaphoreci
  OS support unclear, probably just docker based
  looks enterprisey

buildkite
  OS support:
    Ubuntu
    Debian
    Red Hat / CentOS
    FreeBSD
    Docker
    Mac OS
    Windows

wercker
  oracle something
  OS support unclear, probably just docker based

teamcity
  Linux, macOS, windows, FreeBSD, ...
  https://confluence.jetbrains.com/display/TCD10/Supported+Platforms+and+Environments#SupportedPlatformsandEnvironments-Platforms(OperatingSystems)
  looks weird and bureaucritical
  not sure if service or just software