Alternativer til SlideMail til Ruby med kommerciel licens

• Ruby
  Alle platforme Windows Mac Linux Chrome OS Android iPhone Apple Watch Android Wear iPad Android Tablet Windows S Web Self-Hosted BSD Haiku PortableApps.com Slack F-Droid Chrome Ruby Gmail Cloudron Amazon Echo (Alexa Voice Service) PureOS (Purism)
• Kommerciel licens
  Enhver licens Gratis licens Open Source-licens Kommerciel licens