Triangle.gs is described as 'provides free servers for Minecraft'. There are six alternatives to Triangle.gs, not only websites but also apps for Minecraft Server, Minecraft and Microsoft Azure. The best alternative is Aternos, which is free. Other great sites and apps similar to Triangle.gs are PloudOS (Free), Server.pro (Freemium), GGServers (Paid) and Minehut (Freemium).
This gallery package will set up a preconfigured Minecraft server running on Ubuntu Server 15.04. You can connect to it using the DNS name (e.g. name.cloudapp.net) of the virtual machine on port 25565.