what kind of a server we need to deploy a .war file ? Are there any free trail host providers to check our .war file by deploying?

[Nic Brough -Adaptavist-]

You can't deploy .war files on Atlassian Cloud - it's a managed service, not a hosting provider.

Atlassian no longer provide .war builds for their applications, it's strongly recommended that you deploy them with the installers.

But if you must use a .war, then all you need is a web application server like Tomcat, Glassfish, jboss etc.