Prosody is described as 'modern flexible communications server for Jabber/XMPP written in Lua. It aims to be easy to set up and configure, and light on resources' and is an app in the Social & Communications category. There are nine alternatives to Prosody for a variety of platforms, including Linux, Windows, Mac, Online / Web-based and Android. The best alternative is Matrix.org, which is both free and Open Source. Other great apps like Prosody are MongooseIM platform (Free, Open Source), Openfire (Free, Open Source), ejabberd (Free, Open Source) and Bopup Communication Server (Paid).
Matrix defines a set of open APIs for decentralised communication, suitable for securely publishing, persisting and subscribing to data over a global open federation of servers with no single point of control.
MongooseIM is aimed at large, complex enterprise level projects, where real-time communication is critical for business success. It provides high availability, ease of deployment, development and reliability in production.
ejabberd is an open source Jabber/XMPP server designed from the ground up to be the building bricks of highly critical messaging systems. Designed to be massively scalable, it is used to power web scale deployments across many software industries.
Instant Messaging (IM) server for internal and secure collaboration over corporate and business networks. It provides Active Directory support, message and file archiving, offline messaging and document distribution with a strong encryption of data.
Apache Vysper aims to be a modular, full featured XMPP (Jabber) server. It has highly modular design. The core of XMPP is defined in the standards RFC3920 and RFC3921. XMPP is more commonly known as 'Jabber'.
Jabberd project has been rewritten from the ground up to be scalable, architecturally sound and to support the latest X.M.P.P Extension Protocols coming out of the X.S.F ( XMPP-Standards-Foundation : foundation for XMPP standards ).