Free alternatives to Adobe ColdFusion Server

1) BlueDragon - https://en.wikipedia.org/wiki/BlueDragon

BlueDragon is a ColdFusion Markup Language (CFML) engine comparable to Adobe Systems's ColdFusion. It is licensed and distributed by New Atlanta from TagServlet Ltd based in Scotland.

BlueDragon is also distributed and supported by BEA Systems on their Oracle WebLogic Server server platform.

BlueDragon applications run on a variety of platforms, including Microsoft Windows, Linux, and Mac OS X. It is mostly compatible with ColdFusion MX 7.
In March, 2008 New Atlanta announced that the future versions of BlueDragon (Java EE editions) will be released as open source products

2) Railo - http://en.wikipedia.org/wiki/Railo

Railo Server, commonly referred to as Railo (/raɪloʊ/ raɪ-lo), is open source software which implements the general-purpose CFML server-side scripting language, often used to create dynamic websites, web applications and intranet systems. CFML is a dynamic language supporting multiple programming paradigms and runs on the Java Virtual Machine (JVM).

Railo was created by the Swiss company Railo Technologies GmbH, intended as a high performance alternative to Adobe ColdFusion. In 2008, Railo switched to an open source community-driven model, and became a JBoss project. The Railo Open Source project is led by Railo Technologies, with development work funded by consulting and support contracts, but anyone may contribute code for consideration.

3) http://en.wikipedia.org/wiki/SmithProject

SmithProject was an Open Source CFML script engine.
The Smith Project was initiated by youngculture AG based on a need to migrate a large ColdFusion based web application to a Java-based engine.