Alternativa Greasefireu za Sunbird sa besplatnom licencom

• Sunbird
  Sve platforme Windows Mac Linux Chrome OS Android iPhone Windows Phone Apple Watch iPad Android Tablet Kindle Fire Web Self-Hosted Software as a Service (SaaS) Firefox Opera Safari Vivaldi Browser SeaMonkey BSD PortableApps.com Microsoft Office Outlook Electron / Atom Shell Chrome Microsoft Edge Thunderbird Yandex.Browser Maxthon Sunbird Neovim
• Besplatna licenca
  Bilo koja licenca Besplatna licenca Licenca otvorenog koda Komercijalna licenca